View Filing Data

Equity earnings from unconsolidated affiliates (Note 4)

$ 344

$ 336

$ 341

^[1]

^[1]

Impairment of equity-method investment (Note 4)

(199)

Operation and maintenance expenses

(53)

(54)

(55)

^[1]

Property taxes

(19)

(21)

(23)

^[1]

General and administrative

(9)

^[1]

Financial charges and other (Note 11)

(85)

(86)

^[1]

(56)

(50)

(44)

^[1]

Net income attributable to non-controlling interests

204

191

^[1]

^[1]

Net income attributable to controlling interests

172

155

^[1]

Net income (loss) attributable to controlling interest allocation (Note 12)

General Partner

^[1]

TransCanada and its subsidiaries

^[1]

Net income attributable to controlling interests

172

155

^[1]

Net income (loss) attributable to controlling interest allocation (Note 12)

Limited partners

$ (2)

$ 168

$ 126

^[1]

Net income per common unit (Note 12) - basic (in dollars per unit) | $ / shares

$ (0.03)

$ 2.67

$ 2.13

^[1]

Net income per common unit (Note 12) - diluted (in dollars per unit) | $ / shares

$ (0.03)

$ 2.67

$ 2.13

Weighted average common units outstanding - basic (in units) | shares

63.9

62.7

58.9

^[1]

Weighted average common units outstanding - diluted (in units) | shares

63.9

62.7

58.9

Common units outstanding, end of year (in units) | shares

64.3

63.6

62.3

^[1]

[1]	Recast as discussed in Note 2 and Note 6.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

^[1]

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

Change in fair value of cash flow hedges (Note 18)

$ 20

$ 204

$ 191

Other comprehensive income

(1)

Reclassification to net income of gains and losses on cash flow hedges (Note 10)

Total comprehensive income

203

191

Comprehensive income attributable to non-controlling interests

Comprehensive income attributable to controlling interests

$ 13

$ 171

$ 155

[1]	Recast as discussed in Note 2 and Note 6.

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Cash Generated From Operations

$ 20

$ 204

$ 191

^[1]

Impairment of equity - method investment (Note 4)

^[1]

199

Amortization of debt issue costs (Note 11)

^[1]

Accruals for costs related to acquisition of 49.9% interest in PNGTS (Note 22)

Equity earnings in excess of cumulative distributions

(3)

Equity allowance for funds used during construction

(1)

Change in other long-term liabilities

^[1]

Change in operating working capital (Note 14)

(9)

(8)

^[1]

Total cash generated from operations

294

308

272

^[1]

Acquisition of interests in GTN and Bison, net of cash acquired (Note 6)

(25)

(921)

^[1]

Adjustment to the 2011 Acquisition

^[1]

Capital expenditures

(54)

(10)

(15)

^[1]

Change in affiliate demand loan receivable

^[1]

Other

Total investing activities

(301)

(234)

(920)

^[1]

Financing Activities

Distributions paid (Note 13)

(228)

(212)

(188)

^[1]

Distributions paid to non-controlling interests

(9)

(50)

(52)

^[1]

Change in affiliate demand loan payable

^[1]

(15)

Equity contribution by the General Partner (Note 6)

Long-term debt issued, net of discount (Note 7)

618

937

^[1]

Short-term loan issued (Note 7)

170

Long-term debt repaid (Note 7)

(404)

(89)

(372)

^[1]

Debt issuance costs

(3)

(2)

^[1]

Equity contribution from Bison's former parent (Note 16)

^[1]

Distributions paid to former parent of GTN and Bison

^[1]

(37)

Total financing activities

(73)

670

^[1]

Increase/(decrease) in cash and cash equivalents

^[1]

Cash and cash equivalents, beginning of year

^[1]

Cash and cash equivalents, end of year

^[1]

Interest payments made

^[1]

Supplemental information about non-cash investing and financing activities

Accrual for Carty Lateral consideration payment (Note 6)

^[1]

Accrual for costs related to construction of Carty Lateral (Note 14)

Issuance of Class B units to TransCanada (Note 6)

ATM Equity Issuance Program

Financing Activities

Equity issuance, net (Note 9)

Equity Issuance, May 2013

Financing Activities

Equity issuance, net (Note 9)

^[1]

381

Acquisition of the remaining 30 percent interest (Note 6)

(264)

Bison

Acquisition of the remaining 30 percent interest (Note 6)

(217)

Cumulative distributions in excess of equity earnings

^[1]

Investment in Great Lakes / Northern Border (Note 4)

^[1]

(31)

Cumulative distributions in excess of equity earnings

^[1]

Investment in Great Lakes / Northern Border (Note 4)

$ (9)

^[1]

[1]	Recast as discussed in Note 2 and Note 6.

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - Transaction between entities under common control - Former parent, TransCanada subsidiaries	Jan. 01, 2016	Apr. 01, 2015	Oct. 01, 2014	Jul. 01, 2013
GTN
Acquisitions
Interest acquired (as a percent)		30.00%		45.00%
Bison
Acquisitions
Interest acquired (as a percent)			30.00%	45.00%
Subsequent event \| Portland Natural Gas Transmission System
Acquisitions
Interest acquired (as a percent)	49.90%

CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' EQUITY - USD ($)
shares in Millions, $ in Millions

Limited Partners

Common units

GTN

Limited Partners

Common units

Bison

Limited Partners

Common units

GTN and Bison

Limited Partners

Common units

Equity Issuance, May 2013

Limited Partners

Common units

ATM Equity Issuance Program

Limited Partners

Common units

Limited Partners

Class B units

Unit issuances

Limited Partners

Class B units

General Partner

GTN

General Partner

GTN and Bison

General Partner

Equity Issuance, May 2013

General Partner

ATM Equity Issuance Program

General Partner

Accumulated Other Comprehensive Loss

^[1]

Non-controlling interests

GTN

Non-controlling interests

Bison

Non-controlling interests

Equity of former parent

^[2]

GTN

Bison

GTN and Bison

Equity Issuance, May 2013

ATM Equity Issuance Program

Unit issuances

Total

Partners' Equity at beginning of year at Dec. 31, 2012

$ 1,275

$ 27

$ (1)

$ 448

$ 673

$ 2,422

Partners' Equity at beginning of year (in units) at Dec. 31, 2012

53.5

Increase (Decrease) in Partners' Equity

Net income attributed to former parent of GTN and Bison

$ 152

191

^[2]

(26)

Distributions to former parent of GTN and Bison

(37)

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9)

$ 373

$ 8

$ 381

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9) (in units)

8.8

Acquisition of the remaining interest in GTN, 2015; Bison 2014; Excess purchase price paid over net acquired assets, 2013 (Note 6)

$ (268)

$ (6)

$ (274)

Distributions

(184)

(4)

(52)

(240)

Equity contribution from Bison's former parent (Note 16)

Former parent carrying amount of acquired entities

$ (672)

(672)

Adjustment to the 2011 Acquisition

Other

(1)

Partners' Equity at end of year at Dec. 31, 2013

$ 1,322

(1)

440

1,789

Partners' Equity at end of year (in units) at Dec. 31, 2013

62.3

Increase (Decrease) in Partners' Equity

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9)

$ 168

204

Other Comprehensive Loss

(1)

$ 71

$ 2

$ 73

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9) (in units)

1.3

Acquisition of the remaining interest in GTN, 2015; Bison 2014; Excess purchase price paid over net acquired assets, 2013 (Note 6)

$ (29)

$ (188)

$ (217)

Distributions

(207)

(5)

(50)

(262)

Partners' Equity at end of year at Dec. 31, 2014

$ 1,325

(2)

234

1,586

Partners' Equity at end of year (in units) at Dec. 31, 2014

63.6

Increase (Decrease) in Partners' Equity

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9)

$ (2)

$ 12

$ 43

$ 95

$ 1

$ 44

$ 95

Equity Issuance, net (Note 9); Issuance of Units (Note 6 and 9) (in units)

0.7

1.9

Acquisition of the remaining interest in GTN, 2015; Bison 2014; Excess purchase price paid over net acquired assets, 2013 (Note 6)

$ (124)

$ (3)

$ (232)

$ (359)

Partners' Equity at end of year at Dec. 31, 2015

Distributions

(221)

(7)

$ (9)

(237)

$ 1,021

$ 107

$ 25

$ (2)

$ 1,151

Partners' Equity at end of year (in units) at Dec. 31, 2015

64.3

1.9

[1]	Losses related to cash flow hedges reported in Accumulated Other Comprehensive Loss and expected to be reclassified to net income in the next 12 months are estimated to be $1 million. These estimates assume constant interest rates over time; however, the amounts reclassified will vary based on actual value of interest rates at the date of settlement.
[2]	Recast as discussed in Note 2 and Note 6.

CONSOLIDATED STATEMENT OF CHANGES IN PARTNERS' EQUITY (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Losses related to cash flow hedges reported in Accumulated Other Comprehensive Loss
Losses expected to be reclassified to net income in the next 12 months	$ 1

ORGANIZATION

12 Months Ended

Dec. 31, 2015

ORGANIZATION

ORGANIZATION

NOTE 1 ORGANIZATION

TC PipeLines, LP and its subsidiaries are collectively referred to herein as the Partnership. The Partnership was formed by TransCanada PipeLines Limited, a wholly-owned subsidiary of TransCanada Corporation (TransCanada Corporation together with its subsidiaries collectively referred to herein as TransCanada), to acquire, own and participate in the management of energy infrastructure assets in North America.

The Partnership owns the following interests in natural gas pipeline systems:

Pipeline	Length	Description	Ownership

Gas Transmission Northwest LLC (GTN)	1,377 miles	Extends between an interconnection near Kingsgate, British Columbia, Canada at the Canadian border to a point near Malin, Oregon at the California border and delivers natural gas to the Pacific Northwest and to California.	100 percent
Northern Border Pipeline Company (Northern Border)	1,408 miles	Extends between the Canadian border near Port of Morgan, Montana to a terminus near North Hayden, Indiana, south of Chicago. Northern Border is capable of receiving natural gas from Canada, the Williston Basin and Rocky Mountain area for deliveries to the Midwest. ONEOK Partners, L.P. owns the remaining 50 percent of Northern Border.	50 percent
Bison Pipeline LLC (Bison)	303 miles	Extends from a location near Gillette, Wyoming to Northern Border's pipeline system in North Dakota. Bison transports natural gas from the Powder River Basin to Midwest markets.	100 percent
Great Lakes Gas Transmission Limited Partnership (Great Lakes)	2,115 miles	Connects with the TransCanada Mainline at the Canadian border near Emerson, Manitoba, Canada and St. Clair, Michigan, near Detroit. Great Lakes is a bi-directional pipeline that can receive and deliver natural gas at multiple points along its system. TransCanada owns the remaining 53.55 percent of Great Lakes.	46.45 percent
North Baja Pipeline, LLC (North Baja)	86 miles	Extends between an interconnection with the El Paso Natural Gas Company pipeline near Ehrenberg, Arizona and an interconnection with a natural gas pipeline near Ogilby, California on the Mexican border transporting natural gas in the southwest. North Baja is a bi-directional pipeline.	100 percent
Tuscarora Gas Transmission Company (Tuscarora)	305 miles	Extends between the GTN pipeline near Malin, Oregon to its terminus near Reno, Nevada and delivers natural gas in northeastern California and northwestern Nevada.	100 percent
Portland Natural Gas Transmission System (PNGTS)	295 miles	Connects with the TransQuebec and Maritimes Pipeline (TQM) at the Canadian border to deliver natural gas to customers in the U.S. northeast. TransCanada owns 11.81 percent of PNGTS. Northern New England Investment Company, Inc. owns the remaining 38.29 percent of PNGTS.	49.9 percent(a)


(a)	Effective January 1, 2016 (Refer to Note 22)

The Partnership is managed by its General Partner, TC PipeLines GP, Inc. (General Partner), an indirect wholly-owned subsidiary of TransCanada. The General Partner provides management and operating services for the Partnership and is reimbursed for its costs and expenses. The General Partner owns 5,797,106 common units, 100 percent of our IDRs and an effective two percent general partner interest in the Partnership at December 31, 2015. TransCanada also indirectly holds an additional 11,287,725 common units, for total ownership of 26.6 percent of our outstanding common units and 100 percent of our Class B units at December 31, 2015 (Refer to Note 6).

SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
SIGNIFICANT ACCOUNTING POLICIES	Dec. 31, 2015
SIGNIFICANT ACCOUNTING POLICIES
SIGNIFICANT ACCOUNTING POLICIES	NOTE 2 SIGNIFICANT ACCOUNTING POLICIES The accompanying financial statements and related notes have been prepared in accordance with United States generally accepted accounting principles (GAAP) and amounts are stated in U.S. dollars. The financial statements and notes present the financial position of the Partnership as of December 31, 2015 and 2014 and the results of its operations, cash flows and changes in partners' equity for the years ended December 31, 2015, 2014 and 2013. (a) Basis of Presentation The Partnership consolidates its investments in GTN, Bison, North Baja and Tuscarora, over which it is able to exercise control. To the extent there are interests owned by other parties, these interests are included in non-controlling interests. The Partnership uses the equity method of accounting for its investments in Northern Border and Great Lakes, over which it is able to exercise significant influence. On April 1, 2015 and October 1, 2014, the Partnership acquired the remaining 30 percent interest in GTN and Bison, respectively, from subsidiaries of TransCanada. These acquisitions resulted in GTN and Bison being wholly-owned by the Partnership. Prior to these transactions, the remaining 30 percent interests held by subsidiaries of TransCanada were reflected as non-controlling interests in the Partnership's consolidated financial statements. The acquisitions of these already-consolidated entities were accounted as a transaction between entities under common control, similar to a pooling of interests, whereby the acquired interests were recorded at TransCanada's carrying value and the total excess purchase price paid was recorded as a reduction in Partners' Equity. Refer to Note 6 for additional disclosures regarding these acquisitions. On July 1, 2013, the Partnership acquired a 45 percent membership interest in each of GTN and Bison (the 2013 Acquisition) from subsidiaries of TransCanada increasing the Partnership's ownership in each of GTN and Bison to 70 percent. The 2013 Acquisition was accounted for as a transaction between entities under common control, similar to a pooling of interests, whereby the assets and liabilities of GTN and Bison were recorded at TransCanada's carrying value and the Partnership's historical financial information, except net income per common unit, was recast to consolidate GTN and Bison for all periods presented. Refer to Note 6 for additional disclosure regarding the 2013 Acquisition. (b) Use of Estimates The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Although management believes these estimates are reasonable, actual results could differ from these estimates. (c) Cash and Cash Equivalents The Partnership's cash and cash equivalents consist of cash and highly liquid short-term investments with original maturities of three months or less and are recorded at cost, which approximates fair value. (d) Trade Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. We review our accounts receivable regularly and record allowances for doubtful accounts using the specific identification method. (e) Inventories Inventories primarily consist of materials and supplies and are carried at the lower of weighted average cost or market. (f) Plant, Property and Equipment Plant, property and equipment are stated at original cost. Costs of restoring the land above and around the pipeline are capitalized to pipeline facilities and depreciated over the remaining life of the related pipeline facilities. Pipeline facilities and compression equipment have an estimated useful life of 20 to 77 years and metering and other equipment ranges from 5 to 77 years. Depreciation is calculated on a straight-line composite basis over the assets' estimated useful lives. Repair and maintenance costs are expensed as incurred. Costs that are considered a betterment are capitalized. An allowance for funds used during construction, using the rate of return on rate base approved by the Federal Energy Regulatory Commission (FERC), is capitalized and included in the cost of plant, property and equipment. Amounts included in construction work in progress are not amortized until transferred into service. (g) Impairment of Equity Method Investments We review our equity method investments when a significant event or change in circumstances has occurred that may have an adverse effect on the fair value of each investment. When such events or changes occur, we compare the estimated fair value to the carrying value of the related investment. We calculate the estimated fair value of an investment in an equity method investee using an income approach and market approach. The development of fair value estimates requires significant judgment including estimates of future cash flows, which is dependent on internal forecasts, estimates of the long-term rate of growth for the investee, estimates of the useful life over which cash flows will occur, and determination of weighted average cost of capital. The estimates used to calculate the fair value of an investee can change from year to year based on operating results and market conditions. Changes in these estimates and assumptions could materially affect the determination of fair value and our assessment as to whether an investment in an equity method investee has suffered an impairment. If the estimated fair value of an investment is less than its carrying value, we are required to determine if the decline in fair value is other than temporary. This determination considers the aforementioned valuation methodologies, the length of time and the extent to which fair value has been less than carrying value, the financial condition and near-term prospects of the investee, including any specific events which may influence the operations of the investee, the intent and ability of the holder to retain its investment in the investee for a period of time sufficient to allow for any anticipated recovery in market value, and other facts and circumstances. If the fair value of an investment is less than its carrying value and the decline in value is determined to be other than temporary, we record an impairment charge. During the fourth quarter of 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million (See Note 4 for further information). (h) Impairment of Long-lived Assets The Partnership reviews long-lived assets, such as plant, property and equipment for impairment whenever events or changes in circumstances indicate the carrying value may not be recoverable. If the total of the estimated undiscounted future cash flows is less than the carrying value of the assets, an impairment loss is recognized for the excess of the carrying value over the fair value of the assets. (i) Partners' Equity Costs incurred in connection with the issuance of units are deducted from the proceeds received. (j) Revenue Recognition Transmission revenues are recognized in the period in which the service is provided. When a rate case is pending final FERC approval, a portion of the revenue collected is subject to possible refund. As of December 31, 2015, 2014 and 2013, the Partnership has not recognized any transmission revenue that is subject to possible refund. (k) Income Taxes The Partnership is not subject to federal or state income tax. The tax effect of the Partnership's activities accrues to its partners. The Partnership's taxable income or loss, which may vary substantially from the net income or loss reported in the consolidated statement of income, is includable in the federal income tax returns of each partner. The aggregate difference in the basis of the Partnership's net assets for financial and income tax purposes cannot be readily determined because all information regarding each partner's tax attributes related to the partnership is not available. (l) Acquisitions and Goodwill The Partnership accounts for business acquisitions from third parties using the acquisition method of accounting and, accordingly, the assets and liabilities of the acquired entities are recorded at their estimated fair values at the date of acquisition. The excess of the purchase price over the fair value of net assets acquired is attributed to goodwill. Goodwill is not amortized and is tested on an annual basis for impairment or more frequently if any indicators of impairment are evident. The Partnership initially assesses qualitative factors to determine whether events or changes in circumstances indicate that the goodwill might be impaired. If the Partnership does not conclude that it is more likely than not that fair value of the reporting unit is greater than its carrying value, the first step of the two-step impairment test is performed by comparing the fair value of the reporting unit to its book value, which includes goodwill. If the fair value is less than book value, an impairment is indicated and a second step is performed to measure the amount of the impairment. In the second step, the implied fair value of goodwill is calculated by deducting the recognized amounts of all tangible and intangible net assets of the reporting unit from the fair value determined in the initial assessment. If the carrying value of goodwill exceeds the calculated implied fair value of goodwill, an impairment charge is recorded. The Partnership accounts for business acquisitions between itself and TransCanada as transactions between entities under common control. Using this approach, the assets and liabilities of the acquired entities are recorded at TransCanada's carrying value. In the event recasting is required, the Partnership's historical financial information will be recast, except net income per common unit, to include the acquired entities for all periods presented. If the fair market value paid for the acquired entities is greater than the recorded net assets of the acquired entities, the excess purchase price paid is recorded as a reduction in Partners' Equity. Similarly, if the fair market value paid for the acquired entities is less than the recorded net assets of the acquired entities, the excess of assets acquired is recorded as an increase in Partners' Equity. (m) Fair Value Measurements For cash and cash equivalents, receivables, accounts payable, certain accrued expenses and short-term debt, the carrying amount approximates fair value due to the short maturities of these instruments. For long-term debt instruments and the interest rate swap agreements, fair value is estimated based upon market values (if applicable) or on the current interest rates available to us for debt with similar terms and remaining maturities. Considerable judgment is required in developing these estimates. (n) Derivative Financial Instruments and Hedging Activities The Partnership recognizes all derivative instruments as either assets or liabilities in the balance sheet at their respective fair values. For derivatives designated in hedging relationships, changes in the fair value are either offset through earnings against the change in fair value of the hedged item attributable to the risk being hedged or recognized in accumulated other comprehensive income, to the extent the derivative is effective at offsetting the changes in cash flows being hedged until the hedged item affects earnings. The Partnership only enters into derivative contracts that it intends to designate as a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge). For all hedging relationships, the Partnership formally documents the hedging relationship and its risk management objective and strategy for undertaking the hedge, the hedging instrument, the hedged transaction, the nature of the risk being hedged, how the hedging instrument's effectiveness in offsetting the hedged risk will be assessed prospectively and retrospectively, and a description of the method used to measure ineffectiveness. The Partnership also formally assesses, both at the inception of the hedging relationship and on an ongoing basis, whether the derivatives that are used in hedging relationships are highly effective in offsetting changes in cash flows of hedged transactions. For derivative instruments that are designated and qualify as part of a cash flow hedging relationship, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings. The Partnership discontinues hedge accounting prospectively when it determines that the derivative is no longer effective in offsetting cash flows attributable to the hedged risk, the derivative expires or is sold, terminated, or exercised, the cash flow hedge is de-designated because a forecasted transaction is not probable of occurring, or management determines to remove the designation of the cash flow hedge. In all situations in which hedge accounting is discontinued and the derivative remains outstanding, the Partnership continues to carry the derivative at its fair value on the balance sheet and recognizes any subsequent changes in its fair value in earnings. When it is probable that a forecasted transaction will not occur, the Partnership discontinues hedge accounting and recognizes immediately in earnings gains and losses that were accumulated in other comprehensive income related to the hedging relationship. (o) Asset Retirement Obligation The Partnership recognizes the fair value of a liability for asset retirement obligations in the period in which it is incurred, when a legal obligation exists and a reasonable estimate of fair value can be made. The fair value is added to the carrying amount of the associated asset and the liability is accreted through charges to operating expenses. The scope and timing of asset retirements related to natural gas pipelines is indeterminable. As a result, the Partnership has recorded no asset retirement obligations as of December 31, 2015 and 2014. (p) Government Regulation The Partnership's subsidiaries are subject to regulation by FERC. Under regulatory accounting principles, certain assets or liabilities that result from the regulated ratemaking process may be recorded that would not be recorded under GAAP for non-regulated entities. The timing of recognition of certain revenues and expenses in our regulated business may differ from that otherwise expected under GAAP to appropriately reflect the economic impact of the regulators' decisions regarding revenues and rates. The Partnership regularly evaluates the continued applicability of regulatory accounting, considering such factors as regulatory changes, the impact of competition, and the ability to recover regulatory assets. At December 31, 2015, the Partnership had regulatory assets amounting to $2 million reported as part of accounts receivable and other in the balance sheet representing volumetric fuel tracker assets that are settled with in-kind exchanges with customers continually (2014 – nil). Regulatory liabilities are included in other long-term liabilities (refer to Note 8). Allowance for funds used during construction is capitalized and included in plant, property and equipment. (q) Debt Issuance Costs Costs related to the issuance of debt are deferred and amortized using the effective interest rate method over the term of the related debt.

ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED	12 Months Ended
ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED	Dec. 31, 2015
ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED
ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED	NOTE 3 ACCOUNTING PRONOUNCEMENTS NOT YET ADOPTED Revenue from contracts with customers In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-09 "Revenue from Contracts with Customers (Topic 606)." This guidance supersedes the revenue recognition requirements in Topic 605, Revenue Recognition and most industry-specific guidance. This new guidance requires that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. On July 9, 2015, the FASB voted to defer the effective date by one year to December 15, 2017 for annual reporting periods beginning after that date. The FASB also voted to permit early adoption of the standard, but not before the original effective date of December 15, 2016. This new guidance, once effective, allows two methods in which the amendment can be applied: (1) retrospectively to each prior reporting period presented, or (2) retrospectively with the cumulative effect recognized at the date of initial application. The Partnership is currently evaluating the impact of the adoption of this ASU and has not yet determined the effect on its consolidated financial statements. Consolidation In February 2015, the FASB issued ASU No. 2015-02 "Consolidation (Topic 810)," an amendment of previously issued guidance on consolidation. This updated guidance requires that an entity evaluate whether it should consolidate certain legal entities. All legal entities are subject to reevaluation under the revised consolidation model. This guidance is effective from January 1, 2016 and early application is permitted. Application of this amendment could be performed using a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption. Alternatively, the amendment could be applied retrospectively. The Partnership is currently evaluating the impact of the adoption of this ASU and has not yet determined the effect on its consolidated financial statements. Imputation of interest In April 2015, the FASB issued ASU No. 2015-03 "Interest – Imputation of Interest (Subtopic 835-30)," an amendment of previously issued guidance on imputation of interest. This updated guidance requires debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liabilities, consistent with debt discount or premiums. The recognition and measurement for debt issuance costs would not be affected. This guidance is effective from January 1, 2016 and early application is permitted. This guidance should be adopted on a retrospective basis, wherein the balance sheet of each individual period presented would be adjusted to reflect the period-specific effects of applying the new guidance. The application of this amendment will result in a reclassification of debt issuance costs currently recorded in Other Assets to an offset of their respective debt liabilities. Earnings Per Share In April 2015, the FASB issued ASU No. 2015-06 "Earnings Per Share (Topic 260)," an amendment of previously issued guidance on earnings per share (EPS) as it is being calculated by master limited partnerships. This updated guidance specifies that for purposes of calculating historical EPS under the two-class method, the earnings (losses) of a transferred business before the date of a dropdown transaction should be allocated entirely to the general partner interest, and previously reported EPS of the limited partners would not change as a result of a dropdown transaction. Qualitative disclosures about how the rights to the earnings (losses) differ before and after the dropdown transaction occurs are also required. This guidance is effective from January 1, 2016 and early application is permitted. This guidance should be adopted on a retrospective basis to all financial statements presented. The Partnership does not expect the adoption of this new standard to have a material effect on its consolidated financial statements. Business Combinations In September 2015, the FASB issued ASU No. 2015-16 "Business Combinations (Topic 805)," which replaces the requirement that an acquirer in a business combination account for measurement period adjustments retrospectively with a requirement that an acquirer recognize adjustments to the provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amended guidance requires that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The new guidance is effective January 1, 2016 and will be applied prospectively. The Partnership does not expect the adoption of this new standard to have a material effect on its consolidated financial statements.

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

12 Months Ended

Dec. 31, 2015

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

INVESTMENTS IN UNCONSOLIDATED AFFILIATES

NOTE 4 INVESTMENTS IN UNCONSOLIDATED AFFILIATES

Great Lakes and Northern Border are regulated by FERC and are operated by TransCanada. We use the equity method of accounting for our interests in our equity investees.

		Equity Earnings from Unconsolidated Affiliates(b)			Investment in Unconsolidated Affiliates
		Year ended December 31			December 31
	Ownership Interest at December 31, 2015	Year ended December 31			December 31
(millions of dollars)	Ownership Interest at December 31, 2015	2015	2014	2013	2015		2014

Northern Border(a)	50%	66	69	64	480		505
Great Lakes	46.45%	31	19	3	485	(c)	672

		97	88	67	965		1,177


(a)	Equity earnings from Northern Border is net of the 12-year amortization of a $10 million transaction fee paid to the operator of Northern Border at the time of the Partnership's additional 20 percent acquisition in April 2006.
(b)	Equity Earnings represents our share in investee's earnings and does not include any impairment charge on the equity method investment recorded as a reduction of carrying value of these investments.
(c)	During the fourth quarter of 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million. See discussion below.

Northern Border

The Partnership owns a 50 percent general partner interest in Northern Border. The other 50 percent partnership interest in Northern Border is held by ONEOK Partners, L.P., a publicly traded limited partnership.

TC PipeLines Intermediate Limited Partnership, as one of the general partners, may be exposed to the commitments and contingencies of Northern Border. The Partnership holds a 98.9899 percent limited partnership interest in TC PipeLines Intermediate Limited Partnership.

Northern Border has a FERC-approved settlement agreement which established maximum long-term transportation rates and charges on the Northern Border system effective January 1, 2013. Northern Border is required to file for new rates no later than January 1, 2018.

The Partnership recorded no undistributed earnings from Northern Border for the years ended December 31, 2015, 2014 and 2013.

At December 31, 2015 and 2014, the Partnership had a $117 million difference between the carrying value of Northern Border and the underlying equity in the net assets primarily resulting from the recognition and inclusion of goodwill in the Partnership's investment in Northern Border relating to the Partnership's April 2006 acquisition of an additional 20 percent general partnership interest in Northern Border. As of December 31, 2015, no impairment has been identified in our investment in Northern Border.

The summarized financial information for Northern Border is as follows:

December 31 (millions of dollars)		2015		2014

Assets
Cash and cash equivalents		27		41
Other current assets		33		34
Plant, property and equipment, net		1,124		1,163
Other assets		18		34

		1,202		1,272

Liabilities and Partners' Equity
Current liabilities		39		64
Deferred credits and other		26		22
Long-term debt, including current maturities		411		411
Partners' equity
	Partners' capital	728		777
	Accumulated other comprehensive loss	(2	)	(2	)

		1,202		1,272

Year ended December 31 (millions of dollars)	2015		2014		2013

Transmission revenues	286		293		286
Operating expenses	(70	)	(72	)	(75	)
Depreciation	(60	)	(59	)	(58	)
Financial charges and other	(22	)	(22	)	(23	)

Net income	134		140		130

Great Lakes

The Partnership owns a 46.45 percent general partner interest in Great Lakes. TransCanada owns the other 53.55 percent partnership interest. TC GL Intermediate Limited Partnership, as one of the general partners, may be exposed to the commitments and contingencies of Great Lakes. The Partnership holds a 98.9899 percent limited partnership interest in TC GL Intermediate Limited Partnership.

On November 14, 2013, FERC approved a settlement between Great Lakes and its customers to modify its transportation rates effective November 1, 2013. The settlement increases maximum recourse transportation rates by approximately 21 percent. The settlement also requires that Great Lakes file for new rates to be in effect no later than January 1, 2018.

The Partnership recorded no undistributed earnings from Great Lakes for the years ended December 31, 2015, 2014, and 2013.

The Partnership made equity contributions to Great Lakes of $4 million and $5 million in the first and fourth quarter of 2015, respectively. These amounts represent the Partnership's 46.45 percent share of a $9 million and $10 million cash call from Great Lakes to make scheduled debt repayments.

Despite the recent improvement in income from our investment in Great Lakes since 2013, including favorable current year results, its long-term value has been adversely impacted by the changing natural gas flows in its market region as well as our conclusion in the fourth quarter that other strategic alternatives to increase its utilization or revenue were no longer feasible. As a result, we determined that the carrying value of our investment in Great Lakes was in excess of its fair value and that the decline is not temporary. Accordingly, we concluded that the carrying value of our investment in Great Lakes was impaired.

Our analysis determined that the fair value of our investment in Great Lakes is $465 million, resulting in an impairment charge of $199 million in the fourth quarter of 2015, reflected as Impairment of equity-method investment on our Statement of Income for the year ended December 31, 2015. The impairment charge reduced the difference between the carrying value of our investment in Great Lakes and the underlying equity in the net assets, which was reduced to $260 million at December 31, 2015 (2014 – $458 million) and represents the equity method goodwill remaining in our investment in Great Lakes relating to the Partnership's February 2007 acquisition of a 46.45 percent general partner interest in Great Lakes.

Our assumptions related to the estimated fair value of our remaining equity investment in Great Lakes could be negatively impacted by near and long-term conditions including:


•	future regulatory rate action or settlement,
•	valuation of Great lakes in future transactions,
•	changes in customer demand at Great Lakes for pipeline capacity and services,
•	changes in North American natural gas production in the major producing basins,
•	changes in natural gas prices and natural gas storage market conditions, and
•	changes in other long-term strategic objectives.

There is a risk that adverse changes in these key assumptions could result in additional future impairment of the carrying value of our investment in Great Lakes.

The summarized financial information for Great Lakes is as follows:

December 31 (millions of dollars)	2015	2014

Assets
Current assets	86	66
Plant, property and equipment, net	727	748

	813	814

Liabilities and Partners' Equity
Current liabilities	31	38
Long-term debt, including current maturities	297	316
Partners' equity	485	460

	813	814

Year ended December 31 (millions of dollars)	2015		2014		2013

Transmission revenues	177		146		124
Operating expenses	(59	)	(53	)	(60)
Depreciation	(28	)	(28	)	(31)
Financial charges and other	(23	)	(25	)	(27)

Net income	67		40		6

PLANT, PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2015

PLANT, PROPERTY AND EQUIPMENT

PLANT, PROPERTY AND EQUIPMENT

NOTE 5 PLANT, PROPERTY AND EQUIPMENT

The following table includes plant, property and equipment from our consolidated subsidiaries.

	2015				2014
December 31 (millions of dollars)	Cost	Accumulated Depreciation		Net Book Value	Cost	Accumulated Depreciation		Net Book Value

Pipeline	2,086	(638	)	1,448	2,038	(574	)	1,464
Compression	516	(134	)	382	514	(126	)	388
Metering and other	156	(39	)	117	145	(37	)	108
Construction in progress	2	–		2	8	–		8

	2,760	(811	)	1,949	2,705	(737	)	1,968

ACQUISITIONS

12 Months Ended

Dec. 31, 2015

ACQUISITIONS

ACQUISITIONS

NOTE 6 ACQUISITIONS

2015 GTN Acquisition

On April 1, 2015, the Partnership acquired the remaining 30 percent interest in GTN from a subsidiary of TransCanada (2015 GTN Acquisition), which resulted in GTN being wholly-owned by the Partnership. The total purchase price of the 2015 GTN Acquisition was $446 million plus the final purchase price adjustment of $11 million, for a total of $457 million. The purchase price consisted of $264 million in cash (including the final purchase price adjustment of $11 million), the assumption of $98 million in proportional GTN debt and the issuance of 1,900,000 new Class B units to TransCanada valued at $50 each, representing a limited partner interest in the Partnership with a total value of $95 million.

The Partnership funded the cash portion of the transaction using a portion of the proceeds received on our March 13, 2015 debt offering (refer to Note 7). The Class B units entitle TransCanada to a distribution based on 30 percent of GTN's annual distributions as follows: (i) 100 percent of distributions above $20 million through March 31, 2020; and (ii) 25 percent of distributions above $20 million thereafter. Under the terms of the Partnership Agreement, the Class B distribution will be initially calculated to equal 30 percent of GTN's distributable cash flow for the nine months ended December 31, 2015, less $15 million.

Prior to this transaction, the remaining 30 percent interest held by a subsidiary of TransCanada was reflected as a non-controlling interest in the Partnership's consolidated financial statements. The 2015 GTN Acquisition of this already-consolidated entity was accounted as a transaction between entities under common control, similar to a pooling of interests, whereby the acquired interest was recorded at TransCanada's carrying value and the total excess purchase price paid was recorded as a reduction in Partners' Equity.

The net purchase price was allocated as follows:

(millions of dollars)

Net Purchase Price(a)		359
Less: TransCanada's carrying value of non-controlling interest at April 1, 2015		232

Excess purchase price(b)		127


(a)	Total purchase price of $457 million less the assumption of $98 million of proportional GTN debt by the Partnership.
(b)	The excess purchase price of $127 million was recorded as a reduction in Partners' Equity.

Our General Partner also contributed approximately $2 million to maintain its effective two percent interest in the Partnership.

2014 Bison Acquisition

On October 1, 2014, the Partnership acquired the remaining 30 percent interest in Bison from a subsidiary of TransCanada. The total purchase price of the 2014 Bison Acquisition was $215 million plus purchase price adjustments of $2 million. The acquisition of Bison was financed through combinations of (i) net proceeds from the ATM Program (refer to Note 9), and (ii) short-term financing (refer to Note 7).

Prior to this transaction, the remaining 30 percent interest held by a subsidiary of TransCanada was reflected as non-controlling interest in the Partnership's consolidated financial statements. The 2014 Bison Acquisition of this already-consolidated entity was accounted as a transaction between entities under common control, similar to a pooling of interests, whereby the acquired interest was recorded at TransCanada's carrying value and the total excess purchase price paid was recorded as a reduction in Partners' Equity.

The purchase price was allocated as follows:

(millions of dollars)

Total cash consideration		217
TransCanada's carrying value of non-controlling interest at October 1, 2014		188

Excess purchase price		29

The excess purchase price of $29 million was recorded as a reduction in Partners' Equity.

2013 Acquisition

On July 1, 2013, the Partnership acquired a 45 percent membership interest in each of GTN and Bison from subsidiaries of TransCanada, increasing the Partnership's ownership in each GTN and Bison to 70 percent. The total purchase price of the 2013 Acquisition was $1,050 million plus purchase price adjustments. The purchase price consisted of (i) $750 million for the GTN membership interest (less $146 million, which reflected 45 percent of GTN's outstanding debt at the time of the 2013 Acquisition), (ii) $300 million for the membership interest in Bison, (iii) $17 million in working capital adjustments and (iv) Carty Lateral consideration of $25 million (see below).

The resulting $921 million (after working capital adjustments) paid by the Partnership was financed through a combination of (i) a public offering of 8,855,000 common units at $43.85 per common unit resulting in net proceeds of $373 million (refer to Note 9), (ii) borrowing of $500 million in term loans (refer to Note 7), (iii) a capital contribution from the General Partner of $8 million which was required to maintain the General Partner's effective two percent general partner interest in the Partnership (refer to Note 9), and (iv) a draw on the Partnership's existing $500 million Senior Credit Facility and (v) cash on hand.

Pursuant to the acquisition agreement between the Partnership and TransCanada relating to the Partnership's acquisition of an additional 45 percent membership interest in GTN, the Partnership agreed to make an additional payment of $25 million to TransCanada if Portland General Electric Company executed a firm transportation service agreement by December 31, 2014 containing agreed terms and relating to transportation on GTN's Carty Lateral. On December 11, 2013, Portland General Electric Company executed this firm transportation service agreement and as a result, the Partnership paid an additional $25 million on April 11, 2014.

The 2013 Acquisition was accounted for as a transaction between entities under common control, similar to a pooling of interests, whereby the assets and liabilities of GTN and Bison were recorded at TransCanada's carrying value and the Partnership's historical financial information, except net income per common unit, was recast to consolidate GTN and Bison for all periods presented.

The purchase price was recorded as follows:

(millions of dollars)

Current assets	67
Property, plant and equipment, net	1,792
Other assets	1
Current liabilities	(20	)
Other liabilities	(21	)
Long-term debt	(325	)

	1,494
Non-controlling interest	(448	)
Carrying value of pre-existing 25% interest in each of GTN and Bison	(374	)

Carrying value of acquired 45% interest in each of GTN and Bison	672
Excess purchase price over net assets acquired (includes Carty Lateral consideration)	274

Total cash consideration including $25 million Carty Lateral consideration	946

As the fair market value for the additional 45 percent interests in each of GTN and Bison was greater than the acquired net assets of GTN and Bison by $262 million and $12 million, respectively, the total excess purchase price of $274 million was recorded as a reduction in Partners' Equity, including the Carty Lateral consideration. The retrospective consolidation of GTN and Bison increased net income attributable to controlling interests by $26 million for the year ended December 31, 2013. However, this amount was excluded from equity attributable to controlling interests and the historical net income per common unit was not adjusted as the pre-acquisition earnings was allocated to TransCanada (refer to Note 12).

DEBT AND CREDIT FACILITIES

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

DEBT AND CREDIT FACILITIES

12 Months Ended

Dec. 31, 2015

DEBT AND CREDIT FACILITIES

NOTE 7 DEBT AND CREDIT FACILITIES

December 31 (millions of dollars)	2015	2014

Senior Credit Facility due 2017	200	330
2013 Term Loan Facility due 2018	500	500
Short-Term Loan Facility due 2015	–	170
2015 Term Loan Facility due 2018	170	–
4.65% Unsecured Senior Notes due 2021, net of discount (2015 and 2014 – nil)	350	350
4.375% Unsecured Senior Notes due 2025, net of $1 million discount	349	–
5.09% Unsecured Senior Notes due 2015	–	75
5.29% Unsecured Senior Notes due 2020	100	100
5.69% Unsecured Senior Notes due 2035	150	150
Unsecured Term Loan Facility due 2019	75	–
3.82% Series D Senior Notes due 2017	16	20

	1,910	1,695
Less: current portion	14	249

	1,896	1,446

The Partnership's Senior Credit Facility consists of a $500 million senior revolving credit facility with a banking syndicate, maturing November 20, 2017, under which $200 million was outstanding at December 31, 2015 (2014 – $330 million), leaving $300 million available for future borrowing.

At the Partnership's option, the interest rate on the outstanding borrowings under the Senior Credit Facility may be lenders' base rate or the London Interbank Offered Rate (LIBOR) plus, in either case, an applicable margin that is based on the Partnership's long-term unsecured credit ratings. The Senior Credit Facility permits the Partnership to specify the portion of the borrowings to be covered by specific interest rate options and, for LIBOR-based borrowings, to specify the interest rate period. The Partnership is required to pay a commitment fee based on its credit rating and on the unused principal amount of the commitments under the Senior Credit Facility. The Senior Credit Facility has a feature whereby at any time, so long as no event of default has occurred and is continuing, the Partnership may request an increase in the Senior Credit Facility of up to $250 million, but no lender has an obligation to increase their respective share of the facility.

The LIBOR-based interest rate on the Senior Credit Facility averaged 1.44 percent for the year ended December 31, 2015 (2014 – 1.41 percent; 2013 – 1.44 percent). The interest rate was 1.50 percent at December 31, 2015 (December 31, 2014 – 1.41 percent).

On July 1, 2013, the Partnership entered into a term loan agreement with a syndicate of lenders for a $500 million term loan credit facility (2013 Term Loan Facility). On July 2, 2013, the Partnership borrowed $500 million under the 2013 Term Loan Facility, to pay a portion of the purchase price of the 2013 Acquisition, maturing on July 1, 2018. The 2013 Term Loan Facility bears interest based, at the Partnership's election, on the LIBOR or the base rate plus, in either case, an applicable margin. The base rate equals the highest of (i) SunTrust Bank's prime rate, (ii) 0.50 percent above the federal funds rate and (iii) 1.00 percent above one-month LIBOR. The applicable margin for the term loan is based on the Partnership's senior debt rating and ranges between 1.125 percent and 2.000 percent for LIBOR borrowings and 0.125 percent and 1.000 percent for base rate borrowings.

The LIBOR-based interest rate on the 2013 Term Loan Facility averaged 1.44 percent for the year ended December 31, 2015 (2014 – 1.41 percent). After hedging activity, the interest rate incurred on the Term Loan Facility averaged 1.85 percent for the year ended December 31, 2015 (2014 – 1.82 percent). Prior to hedging activities, the LIBOR-based interest rate was 1.50 percent at December 31, 2015 (December 31, 2014 – 1.41 percent).

On September 30, 2015, the Partnership entered into an agreement for a $170 million term loan credit facility (2015 Term Loan Facility). The Partnership borrowed $170 million under the 2015 Term Loan Facility to refinance its Short-Term Loan Facility which matured on September 30, 2015. The 2015 Term Loan Facility matures on October 1, 2018. The LIBOR-based interest rate on the 2015 Term Loan Facility averaged 1.47 percent for the year ended December 31, 2015. The interest rate was 1.39 percent at December 31, 2015.

The 2013 Term Loan Facility and the 2015 Term Loan Facility (Term Loan Facilities) and the Senior Credit Facility require the Partnership to maintain a certain leverage ratio (debt to adjusted cash flow [net income plus cash distributions received, extraordinary losses, interest expense, expense for taxes paid or accrued, and depreciation and amortization expense less equity earnings and extraordinary gains]). In the quarter in which an acquisition has occurred, and the two quarters following the acquisition, the allowable leverage ratio increases to 5.50 to 1.00. Thereafter, the ratio returns to 5.00 to 1.00. The allowable ratio for the quarter ended December 31, 2015 is 5.50 to 1.00. The leverage ratio was 4.68 to 1.00 as of December 31, 2015. The Senior Credit Facility and the Term Loan Facilities contain additional covenants that include restrictions on entering into mergers, consolidations and sales of assets, granting liens, material amendments to the Partnership Agreement, incurrence of additional debt by the Partnership's subsidiaries and distributions to unitholders. Upon any breach of these covenants, amounts outstanding under the Senior Credit Facility and the Term Loan Facilities may become immediately due and payable.

On March 13, 2015, the Partnership closed a $350 million public offering of senior unsecured notes bearing an interest rate of 4.375 percent maturing March 13, 2025. The net proceeds of $346 million were used to fund a portion of the acquisition of the remaining 30 percent interest in GTN (refer to Note 6) and to reduce the amount outstanding under our Senior Credit Facility. The indenture for the notes contains customary investment grade covenants.

On June 1, 2015, GTN's 5.09 percent unsecured Senior Notes matured. Also, on June 1, 2015, GTN entered into a $75 million unsecured variable rate term loan facility (Unsecured Term Loan Facility), which requires yearly principal payments until its maturity on June 1, 2019. The variable interest is based on LIBOR plus an applicable margin. The LIBOR-based interest rate on the Unsecured Term Loan Facility for the year ended December 31, 2015 averaged 1.16 percent and was 1.15 percent at December 31, 2015. GTN's Unsecured Senior Notes, along with this new Unsecured Term Loan Facility contain a covenant that limits total debt to no greater than 70 percent of GTN's total capitalization. GTN's total debt to total capitalization ratio at December 31, 2015 is 43.8 percent.

The Series D Senior Notes, which require yearly principal payments until its maturity, are secured by Tuscarora's transportation contracts, supporting agreements and substantially all of Tuscarora's property. The note purchase agreements contain certain provisions that include, among other items, limitations on additional indebtedness and distributions to partners.

At December 31, 2015, the Partnership was in compliance with its financial covenants, in addition to the other covenants which include restrictions on entering into mergers, consolidations and sales of assets, granting liens, material amendments to the second amended and restated agreement of limited partnership (Partnership Agreement), incurring additional debt and distributions to unitholders.

The principal repayments required by the Partnership on its debt are as follows:

(millions of dollars)

2016		14
2017		222
2018		690
2019		35
2020		100
Thereafter		849

		1,910

OTHER LIABILITIES

12 Months Ended

Dec. 31, 2015

OTHER LIABILITIES

OTHER LIABILITIES

NOTE 8 OTHER LIABILITIES

December 31 (millions of dollars)	2015	2014

Regulatory liabilities	24	23
Other liabilities	3	3

	27	26

The Partnership collects estimated future removal costs related to its transmission and gathering facilities in its current rates and recognizes regulatory liabilities in this respect in the balance sheet. Estimated costs associated with the future removal of transmission and gathering facilities are collected through depreciation as allowed by FERC. These amounts do not represent asset retirement obligations as defined by FASB ASC 410, Accounting for Asset Retirement Obligations.

PARTNERS' EQUITY	12 Months Ended
PARTNERS' EQUITY	Dec. 31, 2015
PARTNERS' EQUITY
PARTNERS' EQUITY	NOTE 9 PARTNERS' EQUITY At December 31, 2015, the Partnership had 64,317,449 common units outstanding, of which 47,232,618 were held by non-affiliates and 17,084,831 common units were held by subsidiaries of TransCanada, including 5,797,106 common units held by our General Partner. Additionally, TransCanada, through our General Partner, owns 100 percent of our IDRs and an effective two percent general partner interest in the Partnership. TransCanada also holds 100 percent of our 1,900,000 outstanding Class B units. ATM Equity Issuance Program (ATM Program) In August 2014, the Partnership entered into an Equity Distribution Agreement (the EDA) with five different financial institutions (Managers), pursuant to which, the Partnership may from time to time, offer and sell common units having an aggregate offering price of up to $200 million. Sales of such common units will be made by means of ordinary brokers' transactions on the NYSE at market prices, in block transactions or as otherwise agreed upon by one or more of the Managers and the Partnership. In 2015, the Partnership issued 0.7 million common units under the ATM Program generating net proceeds of approximately $43 million, plus an additional $1 million from the General Partner's to maintain its effective two percent interest. The commissions to our sales agents were approximately $0.4 million. The net proceeds were used for general partnership purposes. In 2014, the Partnership issued 1.3 million common units under the ATM Program generating net proceeds of approximately $71 million, plus an additional $2 million from the General Partner's to maintain its effective two percent interest. The commissions to our sales agents were approximately $1 million. The net proceeds were used to finance the 2014 Bison Acquisition (refer to Note 6). Issuance of Class B units On April 1, 2015, we issued Class B units to TransCanada to finance a portion of the 2015 GTN Acquisition. The Class B units entitle TransCanada to an annual distribution which is an amount based on 30 percent of cash distributions from GTN above certain annual thresholds (refer to Note 6). The Class B units contain no mandatory or optional redemption features and are also non-convertible, non-exchangeable, non-voting and rank equally with common units upon liquidation. The Class B units' equity account will be increased by the excess of 30 percent of GTN's distributions over the annual threshold until such amount is declared for distribution and paid in the first quarter beginning 2016 and annually thereafter. Equity issuance in connection with the 2013 Acquisition On May 22, 2013, the Partnership closed a public offering of 8,855,000 common units, including 1,155,000 common units purchased pursuant to the exercise of the underwriters' option to purchase additional common units, at a price to the public of $43.85 per common unit for gross proceeds of $388 million and net proceeds of $373 million after unit issuance costs. The General Partner maintained its effective two percent general partner interest in the Partnership by contributing $8 million to the Partnership in connection with the offering. (Refer to Note 6).

ACCUMULATED OTHER COMPREHENSIVE LOSS

12 Months Ended

Dec. 31, 2015

ACCUMULATED OTHER COMPREHENSIVE LOSS

ACCUMULATED OTHER COMPREHENSIVE LOSS

NOTE 10 ACCUMULATED OTHER COMPREHENSIVE LOSS

The changes in accumulated other comprehensive loss (AOCL) by components are as follows:

(millions of dollars)		Cash flow hedges

Balance at December 31, 2012		(1)
Other comprehensive loss before reclassifications		–
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance at December 31, 2013		(1)
Other comprehensive loss before reclassifications		(1)
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance at December 31, 2014		(2)
Other comprehensive loss before reclassifications		–
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance as of December 31, 2015		(2)

FINANCIAL CHARGES AND OTHER

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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-Section 45
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+ Details

FINANCIAL CHARGES AND OTHER

12 Months Ended

Dec. 31, 2015

FINANCIAL CHARGES AND OTHER

NOTE 11 FINANCIAL CHARGES AND OTHER

Year ended December 31 (millions of dollars)	2015		2014		2013(a)

Interest expense	58		48		42
Amortization of debt issue costs	1		1		1
Net realized loss related to the interest rate swaps and options	2		2		1
Other	(5	)	(1	)	–

	56		50		44


(a)	Recast as discussed in Note 2 and Note 6.

NET INCOME (LOSS) PER COMMON UNIT

12 Months Ended

Dec. 31, 2015

NET INCOME (LOSS) PER COMMON UNIT

NET INCOME (LOSS) PER COMMON UNIT

NOTE 12 NET INCOME (LOSS) PER COMMON UNIT

Net income (loss) per common unit is computed by dividing net income attributable to controlling interests, after deduction of amounts attributable to the General Partner and to TransCanada and its subsidiaries, by the weighted average number of common units outstanding.

The amounts allocable to the General Partner equals an amount based upon the General Partner's effective two percent general partner interest, plus an amount equal to incentive distributions. Incentive distributions are paid to the General Partner if quarterly cash distributions on the common units exceed levels specified in the Partnership Agreement (refer to Note 13).

The amounts allocable to TransCanada and its subsidiaries represents amount allocable to the Class B units (refer to Note 6-2015 GTN Acquisition) and amounts allocable to GTN and Bison's former parent as a result of recast (refer to Note 6- 2013 Acquisition).

The amount allocable to GTN and Bison's former parent represents income of GTN and Bison prior to the 2013 Acquisition.

The amount allocable to the Class B units in 2015 equals an amount based upon 30 percent of GTN's distributable cash flow during the nine months ended December 31, 2015 less $15 million.

Net income (loss) per common unit was determined as follows:

(millions of dollars, except per common unit amounts)	2015		2014	2013(a)

Net income allocable to controlling interests	13		172	155
Net income attributable to GTN's and Bison's former parent	–		–	26	(b)

Net income allocable to General and Limited Partners(b)	13		172	129
Incentive distributions attributable to the General Partner(c)	3		1	–
Net income attributable to the Class B units(d)	12		–	–

Net income (loss) allocable to the General Partner and common units	(2	)	171	129
Net Income (loss) allocable to the General Partner's two percent interest	–		3	3

Net income (loss) attributable to common units	(2	)	168	126

Weighted average common units outstanding (millions) – basic and diluted	63.9		62.7	58.9
Net income (loss) per common unit – basic and diluted	$ (0.03	)	$ 2.67	$ 2.13


(a)	Recast as discussed in Note 2 and Note 6.
(b)	Net income allocable to General and Limited Partners excludes net income attributed to GTN's and Bison's former parent as it was allocated to TransCanada and was not allocable to either the general partner, common units or Class B units (refer to Note 6 – 2013 Acquisition).
(c)	Net income allocable to General and Limited Partners is allocated based on their respective participation rights, after giving effect to any priority income allocation for incentive distributions that are allocated 100 percent to the General Partner. Under the terms of the Partnership Agreement, for any quarterly period, the participation of the IDRs is limited to the available cash distributions declared. Accordingly, incentive distributions allocated to the General Partner was based from the Partnership's available cash during the current reporting period, but declared and paid in the subsequent reporting period.
(d)	As discussed in Notes 6 and 9, the Class B units entitle TransCanada to a distribution which is an amount based on 30 percent of GTN's distributions after achieving certain annual thresholds. The distribution will be payable in the first quarter with respect to the prior year's distributions. Consistent with the application of Accounting Standards Codification (ASC) Topic 260 – "Earnings per share," the Partnership allocated a portion of net income attributable to controlling interests to the Class B units upon 30 percent of GTN's total distributable cash flows exceeding $15 million for the nine month period ended December 31, 2015. During the nine months ended December 31, 2015, 30 percent of GTN's total distributable cash flow was $27 million. As a result, $12 million of net income attributable to controlling interests was allocated to the Class B units in 2015. On February 12, 2016, this amount was paid to TransCanada (Refer to Note 13 and 22).

CASH DISTRIBUTIONS

12 Months Ended

Dec. 31, 2015

CASH DISTRIBUTIONS

CASH DISTRIBUTIONS

NOTE 13 CASH DISTRIBUTIONS

The Partnership makes cash distributions to its partners with respect to each calendar quarter within 45 days after the end of each quarter. Distributions are based on Available Cash, as defined in the Partnership Agreement, which includes all cash and cash equivalents of the Partnership and working capital borrowings less reserves established by the General Partner.

Pursuant to the Partnership Agreement, the General Partner receives two percent of all cash distributions in regard to its general partner interest and is also entitled to incentive distributions as described below. The unitholders receive the remaining portion of the cash distribution.

The following table illustrates the percentage allocations of available cash from operating surplus between the common unitholders and our General Partner based on the specified target distribution levels. The percentage interests set forth below for our General Partner include its two percent general partner interest and IDRs, and assume our General Partner has contributed any additional capital necessary to maintain its two percent general partner interest. The distribution to the General Partner illustrated below, other than in its capacity as a holder of 5,797,106 common units that are in excess of its effective two percent general partner interest, represents the IDRs.

		Marginal Percentage Interest in Distribution
	Total Quarterly Distribution Per Unit Target Amount	Common Unitholders	General Partner

Minimum Quarterly Distribution	$0.45	98%	2%
First Target Distribution	above $0.45 up to $0.81	98%	2%
Second Target Distribution	above $0.81 up to $0.88	85%	15%
Thereafter	above $0.88	75%	25%

The following table provides information about our distributions (in millions, except per unit distributions amounts).

					Limited Partners			General Partner
Declaration Date		Payment Date		Per Unit Distribution	Common Units	Class B Units(c)		2%	IDRs(a)	Total Cash Distribution

1/17/2013		2/14/2013		$ 0.78	$ 42	$–		$ 1	$–	$ 43
4/23/2013		5/15/2013		$ 0.78	$ 42	$–		$ 1	$–	$ 43
7/23/2013		8/14/2013		$ 0.81	$ 50	$–		$ 1	$–	$ 51
10/24/2013		11/14/2013		$ 0.81	$ 50	$–		$ 1	$–	$ 51
1/16/2014		2/14/2014		$ 0.81	$ 50	$–		$ 1	$–	$ 51
4/25/2014		5/15/2014		$ 0.81	$ 51	$–		$ 1	$–	$ 52
7/23/2014		8/14/2014		$ 0.84	$ 53	$–		$ 1	$–	$ 54
10/23/2014		11/14/2014		$ 0.84	$ 53	$–		$ 1	$ 1	$ 55
1/22/2015		2/13/2015		$ 0.84	$ 54	$–		$ 1	$–	$ 55
4/23/2015		5/15/2015		$ 0.84	$ 54	$–		$ 1	$–	$ 55
7/23/2015		8/14/2015		$ 0.89	$ 56	$–		$ 2	$ 1	$ 59
10/22/2015		11/13/2015		$ 0.89	$ 57	$–		$ 1	$ 1	$ 59
1/21/2016	(b)	2/12/2016	(b)	$ 0.89	$ 57	$ 12	(d)	$ 1	$ 1	$ 71


(a)	The distributions paid for the year ended December 31, 2015 included incentive distributions to the General Partner of $2 million (2014 – $1 million). There were no incentive distributions paid to the General Partner in the year ended December 31, 2013.
(b)	On February 12, 2016, we paid a cash distribution of $0.89 per unit on our outstanding common units to unitholders of record at the close of business on February 2, 2016 (refer to Note 22).
(c)	The Class B units issued by us on April 1, 2015 represent limited partner interests in us and entitle TransCanada to an annual distribution which is an amount based on 30 percent of GTN's annual distributions after achieving certain annual thresholds (refer to Note 6 and 9).
(d)	On February 12, 2016, we paid TransCanada $12 million representing 30 percent of GTN's total distributable cash flows for the nine months ended December 31, 2015 less $15 million (refer to Note 9 and 22).

CHANGE IN OPERATING WORKING CAPITAL

12 Months Ended

Dec. 31, 2015

CHANGE IN OPERATING WORKING CAPITAL

CHANGE IN OPERATING WORKING CAPITAL

NOTE 14 CHANGE IN OPERATING WORKING CAPITAL

Year Ended December 31 (millions of dollars)	2015		2014(a)	2013(a)

Change in accounts receivable and other	–		2	1
Change in accounts payable and accrued liabilities	(3)		4	(9	)
Change in accounts payable to affiliates	(10)	(b)	11	(2	)
Change in accrued interest	4		–	2

Change in operating working capital	(9)		17	(8	)


(a)	Recast as discussed in Note 2 and Note 6.
(b)	Excludes certain non-cash items primarily related to accruals of $10 million for construction of GTN's Carty Lateral and $2 million for costs related to acquisition of 49.9 percent interest in PNGTS (Note 22).

TRANSACTIONS WITH MAJOR CUSTOMERS

12 Months Ended

Dec. 31, 2015

TRANSACTIONS WITH MAJOR CUSTOMERS

TRANSACTIONS WITH MAJOR CUSTOMERS

NOTE 15 TRANSACTIONS WITH MAJOR CUSTOMERS

The following table shows revenues from the Partnership's major customers comprising more than 10 percent of the Partnership's total revenues for the years ended December 31, 2015, 2014 and 2013:

Year Ended December 31 (millions of dollars)	2015	2014	2013(a)

Anadarko Energy Services Company (Anadarko)	48	48	48
Pacific Gas and Electric Company (Pacific Gas)	42	45	46


(a)	Recast as discussed in Note 2 and Note 6.

At December 31, 2015, Anadarko and Pacific Gas owed the Partnership approximately $4 million and $3 million, respectively, which is greater than 10 percent of our Trade accounts receivable. At December 31, 2014, Anadarko and Pacific Gas each owed the Partnership approximately $4 million, which is greater than 10 percent of our Trade accounts receivable.

RELATED PARTY TRANSACTIONS

12 Months Ended

Dec. 31, 2015

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS

NOTE 16 RELATED PARTY TRANSACTIONS

The Partnership does not have any employees. The management and operating functions are provided by the General Partner. The General Partner does not receive a management fee in connection with its management of the Partnership. The Partnership reimburses the General Partner for all costs of services provided, including the costs of employee, officer and director compensation and benefits, and all other expenses necessary or appropriate to the conduct of the business of, and allocable to, the Partnership. Such costs include (i) overhead costs (such as office space and equipment) and (ii) out-of-pocket expenses related to the provision of such services. The Partnership Agreement provides that the General Partner will determine the costs that are allocable to the Partnership in any reasonable manner determined by the General Partner in its sole discretion. Total costs charged to the Partnership by the General Partner were $3 million for each of the years ended December 31, 2015, 2014 and 2013.

As operator, TransCanada's subsidiaries provide capital and operating services to GTN, Northern Border, Bison, Great Lakes, North Baja and Tuscarora (together, "our pipeline systems"). TransCanada's subsidiaries incur costs on behalf of our pipeline systems, including, but not limited to, employee salary and benefit costs, and property and liability insurance costs.

Capital and operating costs charged to our pipeline systems for the years ended December 31, 2015, 2014 and 2013 by TransCanada's subsidiaries and amounts payable to TransCanada's subsidiaries at December 31, 2015 and 2014 are summarized in the following tables:

Year ended December 31 (millions of dollars)		2015	2014	2013

Capital and operating costs charged by TransCanada's subsidiaries to:
	GTN(a)(b)	30	30	28
	Northern Border(a)	36	35	30
	Bison(a)(b)(d)	4	6	5
	Great Lakes(a)	30	30	31
	North Baja	5	5	4
	Tuscarora	4	4	4
Impact on the Partnership's net income attributable to controlling interests:
	GTN(b)(c)	25	19	19
	Northern Border	14	16	14
	Bison(b)(d)	4	4	4
	Great Lakes	13	13	14
	North Baja	5	4	4
	Tuscarora	4	4	4

December 31 (millions of dollars)		2015	2014

Amount payable to TransCanada's subsidiaries for costs charged in the year by:
	GTN(a)	3	10
	Northern Border(a)	5	10
	Bison(a)	–	2
	Great Lakes(a)	3	9
	North Baja	–	1
	Tuscarora	1	1


(a)	Represents 100 percent of the costs.
(b)	Recast as discussed in Note 2 and Note 6.
(c)	In 2015, the Partnership acquired remaining 30 percent interest in GTN (Refer to Note 6).
(d)	In 2014, the Partnership acquired remaining 30 percent interest in Bison (Refer to Note 6).

Great Lakes' earns transportation revenues from TransCanada and its affiliates, some of which are provided at discounted rates and some at maximum recourse rates. Great Lakes earned $125 million of transportation revenues under these contracts in 2015 (2014 – $71 million; 2013 – $68 million). This amount represents 71 percent of total revenues earned by Great Lakes in 2015 (2014 – 49 percent; 2013 – 55 percent). Great Lakes also earned $2 million in affiliated rental revenue in 2015 (2014 – $2 million and 2013 – $1 million).

Revenue from TransCanada and its affiliates of $59 million is included in the Partnership's equity earnings from Great Lakes in 2015 (2014 – $34 million; 2013 – $32 million). At December 31, 2015, $17 million was included in Great Lakes' receivables in regards to the transportation contracts with TransCanada and its affiliates (2014 – $15 million).

Effective November 1, 2014, Great Lakes executed contracts with an affiliate, ANR Pipeline Company (ANR), to provide firm service in Michigan and Wisconsin. These contracts were at the maximum FERC authorized rate and were intended to replace historical contracts. On December 3, 2014, the FERC accepted and suspended Great Lakes' tariff records to become effective May 3, 2015, subject to refund. On February 2, 2015, FERC issued an Order granting a rehearing and clarification request submitted by Great Lakes, which allowed additional time for FERC to consider Great Lakes' request. Following extensive discussions with numerous shippers and other stakeholders, on April 20, 2015, ANR filed a settlement with FERC that included an agreement by ANR to pay Great Lakes the difference between the historical and maximum rates (ANR Settlement). Great Lakes provided service to ANR under multiple service agreements and rates through May 3, 2015 when Great Lakes' tariff records became effective and subject to refund. Great Lakes deferred an approximate $9 million of revenue related to services performed in 2014 and approximately $14 million of additional revenue related to services performed through May 3, 2015 under such agreements. On October 15, 2015, FERC accepted and approved the ANR Settlement. As a result, Great Lakes recognized the deferred transportation revenue of approximately $23 million in the fourth quarter of 2015.

Bison's former parent, TransCanada, made an equity contribution to Bison of $18 million in the second quarter of 2013. This amount represents the TransCanada's 75 percent share of a $24 million cash call from Bison to repay inter-affiliate debt primarily related to pipeline construction costs, including reclamation and restoration work.

Effective October 1, 2013, GTN and Bison participated in the Partnership's cash management program. Prior to this, GTN and Bison were part of TransCanada's cash management program. This program matches short-term cash surpluses and borrowing requirements of participating subsidiaries, thus minimizing total borrowing from outside sources. Funds advanced under the program are considered to be a loan, accruing interest and repayable on demand. GTN and Bison will receive interest on funds advanced to the Partnership at the rate of interest earned by the Partnership on its short-term cash investments and will pay interest on funds advanced from the Partnership based on the Partnership's short-term borrowing costs. At December 31, 2015 and 2014, GTN and Bison did not have any demand loan receivable from an affiliate or a demand loan payable to an affiliate.

QUARTERLY FINANCIAL DATA (unaudited)

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

QUARTERLY FINANCIAL DATA (unaudited)

12 Months Ended

Dec. 31, 2015

QUARTERLY FINANCIAL DATA (unaudited)

NOTE 17 QUARTERLY FINANCIAL DATA (unaudited)

The following sets forth selected unaudited financial data for the four quarters in 2015 and 2014:

Quarter ended (millions of dollars except per common unit amounts)	Mar 31	Jun 30	Sept 30	Dec 31

2015
Transmission revenues	87	85	83	89
Equity earnings(a)	31	15	17	34
Impairment of equity-method investment(b)	–	–	–	(199)
Net income (loss)	64	44	49	(137)
Net income (loss) attributable to controlling interests	57	44	49	(137)
Net income (loss) per common unit	$ 0.88	$ 0.66	$ 0.70	(2.24)
Cash distribution paid	55	55	59	59

2014
Transmission revenues	87	82	80	87
Equity earnings(a)	33	18	15	22
Net income	67	45	39	53
Net income attributable to controlling interests	57	37	31	47
Net income per common unit	$ 0.90	$ 0.58	$ 0.48	$ 0.71
Cash distributions paid	51	52	54	55


(a)	Equity Earnings represents our share in investee's earnings and does not include any impairment charge on equity method goodwill included as part of the carrying value of our investments in unconsolidated affiliates.
(b)	During the three months ended December 31, 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million. No impairment has been identified on our investment in Northern Border (Refer to Note 4).

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2015

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS

NOTE 18 FAIR VALUE MEASUREMENTS

(a) Fair Value Hierarchy

Under ASC 820, Fair Value Measurements and Disclosures, fair value measurements are characterized in one of three levels based upon the input used to arrive at the measurement. The three levels of the fair value hierarchy are as follows:


•	Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date.
•	Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.
•	Level 3 inputs are unobservable inputs for the asset or liability.

When appropriate, valuations are adjusted for various factors including credit considerations. Such adjustments are generally based on available market evidence. In the absence of such evidence, management's best estimate is used.

(b) Fair Value of Financial Instruments

The carrying value of cash and cash equivalents, accounts receivable and other, accounts payable and accrued liabilities, accounts payable to affiliates, accrued interest and short-term debt approximate their fair values because of the short maturity or duration of these instruments, or because the instruments bear a variable rate of interest or a rate that approximates current rates. The fair value of the Partnership's long-term debt is estimated by discounting the future cash flows of each instrument at estimated current borrowing rates. The fair value of interest rate derivatives is calculated using the income approach which uses period-end market rates and applies a discounted cash flow valuation model.

The estimated fair value of the Partnership's debt as at December 31, 2015 and 2014 are as follows:

	2015		2014
December 31 (millions of dollars)	Carrying Value	Fair Value	Carrying Value	Fair Value

Senior Credit Facility due 2017	200	200	330	330
2013 Term Loan Facility due 2018	500	500	500	500
Short-Term Loan Facility due 2015	–	–	170	170
2015 Term Loan Facility due 2018	170	170	–	–
4.65% Unsecured Senior Notes due 2021	350	338	350	375
4.375% Unsecured Senior Notes due 2025	349	314	–	–
5.09% Unsecured Senior Notes due 2015	–	–	75	76
5.29% Unsecured Senior Notes due 2020	100	108	100	111
5.69% Unsecured Senior Notes due 2035	150	151	150	168
Unsecured Term Loan Facility due 2019	75	75	–	–
3.82% Series D Senior Notes due 2017	16	17	20	21

	1,910	1,873	1,695	1,751

Long-term debt is recorded at amortized cost and classified in Level II of the fair value hierarchy for fair value disclosure purposes. Interest rate derivative assets and liabilities are classified in Level II for all periods presented where the fair value is determined by using valuation techniques that refer to observable market data or estimated market prices.

Market risk is the risk that changes in market interest rates may result in fluctuations in the fair values or cash flows of financial instruments. The Partnership's floating rate debt is subject to LIBOR benchmark interest rate risk. The Partnership uses interest rate derivatives to manage its exposure to interest rate risk. We regularly assess the impact of interest rate fluctuations on future cash flows and evaluate hedging opportunities to mitigate our interest rate risk.

The Partnership hedged interest payments on $150 million of our $500 million variable-rate 2013 Term Loan Facility with interest rate swaps effective September 3, 2013 and maturing July 1, 2018, at a weighted average fixed interest rate of 2.79 percent. The interest rate swaps are structured such that the cash flows of the derivative instruments match those of the variable rate of interest on the 2013 Term Loan Facility. At December 31, 2015 and 2014, the fair value of the interest rate swaps accounted for as cash flow hedges was a liability of $1 million (both on a gross and net basis) (December 31, 2013 – less than $1 million). In 2015, the Partnership did not record any amounts in net income related to ineffectiveness for interest rate hedges. The change in fair value of interest rate derivative instruments recognized in other comprehensive income was nil million for the year ended December 31, 2015 (2014 – $1 million; 2013 – less than $1 million). In 2015, the net realized loss related to the interest rate swaps was $2 million and was included in financial charges and other (2014 – $2 million; 2013 – $1 million).

The Partnership has no master netting agreements, however, contracts contain provisions with rights of offset. The Partnership has elected to present the fair value of derivative instruments with the right to offset on a gross basis in the balance sheet. Had the Partnership elected to present these instruments on a net basis, there would be no effect on the consolidated balance sheet as of December 31, 2015 and 2014.

Counterparty credit risk represents the financial loss that the Partnership would experience if a counterparty to a financial instrument failed to meet its obligations in accordance with the terms and conditions of the financial instruments with the Partnership. Our maximum counterparty credit exposure with respect to financial instruments at the balance sheet date consists primarily of the carrying amount, which approximates fair value, of non-derivative financial assets, such as accounts receivable, as well as the fair value of derivative financial assets. We review our accounts receivable regularly and record allowances for doubtful accounts using the specific identification method. At December 31, 2015, we had not incurred any significant credit losses and had no significant amounts past due or impaired. At December 31, 2015 and 2014, the Partnership's maximum counterparty credit exposure consisted of accounts receivable of $35 million.

As discussed more fully in Note 4, we recognized $199 million impairment to our equity investment in Great Lakes during the fourth quarter of 2015, reflected as Impairment of equity-method investment on our Statement of Income for the year ended December 31, 2015. The estimated fair value measurement of this investment is classified as Level 3. In the determination of the fair value, we used an income and market approach based on internal forecasts on expected future cash flows and applied appropriate discount rates. The determination of expected future cash flows involved significant assumptions and estimates regarding revenue, operating and maintenance costs and future growth capital.

ACCOUNTS RECEIVABLE AND OTHER

12 Months Ended

Dec. 31, 2015

ACCOUNTS RECEIVABLE AND OTHER

ACCOUNTS RECEIVABLE AND OTHER

NOTE 19 ACCOUNTS RECEIVABLE AND OTHER

December 31 (millions of dollars)	2015	2014

Trade accounts receivable, net of allowance of nil	31	30
Accounts receivable from affiliates	–	1
Other	4	4

	35	35

REGULATORY MATTERS	12 Months Ended
REGULATORY MATTERS	Dec. 31, 2015
REGULATORY MATTERS
REGULATORY MATTERS	NOTE 20 REGULATORY MATTERS North Baja – On January 6, 2014, FERC approved North Baja's application to temporarily abandon compression associated with the original design of its pipeline system. This temporary abandonment will preserve replacement options while reducing maintenance requirements and related expenses without any reduction in capacity or impact to existing firm transportation service. Tuscarora – On January 21, 2016, the FERC issued an Order (the January 21 Order) initiating an investigation pursuant to Section 5 of the Natural Gas Act (NGA) to determine whether Tuscarora's existing rates for jurisdictional services are just and reasonable. Tuscarora is currently preparing its response as required by the January 21 Order. We cannot predict the outcome or potential impact of this proceeding to Tuscarora at this time.

CONTINGENCIES	12 Months Ended
CONTINGENCIES	Dec. 31, 2015
CONTINGENCIES
CONTINGENCIES	NOTE 21 CONTINGENCIES Employees Retirement System of the City of St. Louis v. TC PipeLines GP, Inc., et al. On October 13, 2015, an alleged unitholder of the Partnership filed a class action and derivative complaint in the Delaware Court of Chancery against the General Partner, TransCanada American Investments, Ltd. (TAIL) and TransCanada, and the Partnership as a nominal defendant. The complaint alleges direct and derivative claims for breach of contract, breach of the duty of good faith and fair dealing, aiding and abetting breach of contract, and tortious interference in connection with the 2015 GTN Acquisition, including the issuance by the Partnership of $95 million in Class B Units and amendments to the Partnership Agreement to provide for the issuance of the Class B Units. Plaintiff seeks, among other things, to enjoin future issuances of Class B Units to TransCanada or any of its subsidiaries, disgorgement of certain distributions to the General Partner, TransCanada and any related entities, return of some or all of the Class B Units to the Partnership, rescission of the amendments to the Partnership Agreement, monetary damages and attorney fees. The Partnership has moved to dismiss the complaint and intends to defend vigorously against the claims asserted.

Schedule of ownership interests in natural gas pipeline systems

The entire disclosure for loss and gain contingencies. Describes any existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible loss incurred by an entity that will ultimately be resolved when one or more future events occur or fail to occur, and typically discloses the amount of loss recorded or a range of possible loss, or an assertion that no reasonable estimate can be made.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14472-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12021-110248

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12053-110248

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14453-108349

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14615-108349

+ Details

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2015
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	NOTE 22 SUBSEQUENT EVENTS Management of the Partnership has reviewed subsequent events through February 26, 2016, the date the financial statements were issued, and concluded there were no events or transactions during this period that would require recognition or disclosure in the consolidated financial statements other than what is disclosed here and/or those already disclosed in the preceding notes. On January 21, 2016, the board of directors of our General Partner declared the Partnership's fourth quarter 2015 cash distribution in the amount of $0.89 per common unit. The fourth quarter cash distribution, which was paid on February 12, 2016 to unitholders of record as of February 2, 2016, totaled $59 million and was paid in the following manner: $57 million to common unitholders (including $5 million to the General Partner as holder of 5,797,106 common units and $10 million to another subsidiary of TransCanada as holder of 11,287,725 common units) and $2 million to the General Partner in respect of its effective two percent general partner interest, which included IDRs of $1 million. On January 21, 2016, the board of directors of our General Partner declared distributions to Class B unitholders in the amount of $12 million and was paid on February 12, 2016. The Class B distribution represents an amount based upon 30 percent of GTN's distributable cash flow during the nine months ended December 31, 2015 less $15 million. Northern Border declared its fourth quarter 2015 distribution of $44 million on January 11, 2016, of which the Partnership received its 50 percent share or $22 million. The distribution was paid on February 1, 2016. Great Lakes declared its fourth quarter 2015 distribution of $42 million on January 11, 2016, of which the Partnership received its 46.45 percent share or $20 million. The distribution was paid on February 1, 2016. On January 1, 2016, the Partnership acquired a 49.9 percent interest in PNGTS from a subsidiary of TransCanada (PNGTS Acquisition). The total purchase price of the PNGTS Acquisition was $223 million plus preliminary purchase price adjustments of $3 million. The purchase price consisted of $191 million in cash (including the preliminary purchase price adjustment of $3 million) and the assumption of $35 million in proportional PNGTS debt. The Partnership funded the cash portion of the transaction using proceeds received from our ATM program and additional borrowings under our Senior Credit Facility. The purchase agreement provides for additional payments to TransCanada ranging from $5 million up to a total of $50 million if pipeline capacity is expanded to various thresholds during the fifteen year period following the date of closing. The Partnership will account for this acquisition as a transaction between entities under common control (refer to Note 2 – Significant accounting policies) PNGTS is a high-capacity, high-pressure interstate natural gas pipeline which began serving New England's energy needs in March, 1999. The pipeline connects with the TQM at the Canadian border and shares facilities with the Maritimes and Northeast Pipeline from Westbrook, Maine to a connection with the Tennessee Gas Pipeline System near Boston, Massachusetts. On January 25, 2016, the Partnership hedged interest payments on the remaining $350 million of the $500 million variable-rate 2013 Term Loan Facility with interest rate swaps from January 27, 2016 through July 1, 2018, where the weighted average fixed rate paid is 2.10 percent. The interest rate swaps are structured such that the cash flows of the derivative instruments match those of the variable rate of interest on the 2013 Term Loan Facility.

SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Dec. 31, 2015
SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation - Consolidation and equity method of accounting	(a) Basis of Presentation The Partnership consolidates its investments in GTN, Bison, North Baja and Tuscarora, over which it is able to exercise control. To the extent there are interests owned by other parties, these interests are included in non-controlling interests. The Partnership uses the equity method of accounting for its investments in Northern Border and Great Lakes, over which it is able to exercise significant influence.
Basis of Presentation - Transactions between entities under common control	(a) Basis of Presentation On April 1, 2015 and October 1, 2014, the Partnership acquired the remaining 30 percent interest in GTN and Bison, respectively, from subsidiaries of TransCanada. These acquisitions resulted in GTN and Bison being wholly-owned by the Partnership. Prior to these transactions, the remaining 30 percent interests held by subsidiaries of TransCanada were reflected as non-controlling interests in the Partnership's consolidated financial statements. The acquisitions of these already-consolidated entities were accounted as a transaction between entities under common control, similar to a pooling of interests, whereby the acquired interests were recorded at TransCanada's carrying value and the total excess purchase price paid was recorded as a reduction in Partners' Equity. Refer to Note 6 for additional disclosures regarding these acquisitions. On July 1, 2013, the Partnership acquired a 45 percent membership interest in each of GTN and Bison (the 2013 Acquisition) from subsidiaries of TransCanada increasing the Partnership's ownership in each of GTN and Bison to 70 percent. The 2013 Acquisition was accounted for as a transaction between entities under common control, similar to a pooling of interests, whereby the assets and liabilities of GTN and Bison were recorded at TransCanada's carrying value and the Partnership's historical financial information, except net income per common unit, was recast to consolidate GTN and Bison for all periods presented. Refer to Note 6 for additional disclosure regarding the 2013 Acquisition.
Use of Estimates	(b) Use of Estimates The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Although management believes these estimates are reasonable, actual results could differ from these estimates.
Cash and Cash Equivalents	(c) Cash and Cash Equivalents The Partnership's cash and cash equivalents consist of cash and highly liquid short-term investments with original maturities of three months or less and are recorded at cost, which approximates fair value.
Trade Accounts Receivable	(d) Trade Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. We review our accounts receivable regularly and record allowances for doubtful accounts using the specific identification method.
Inventories	(e) Inventories Inventories primarily consist of materials and supplies and are carried at the lower of weighted average cost or market.
Plant, Property and Equipment	(f) Plant, Property and Equipment Plant, property and equipment are stated at original cost. Costs of restoring the land above and around the pipeline are capitalized to pipeline facilities and depreciated over the remaining life of the related pipeline facilities. Pipeline facilities and compression equipment have an estimated useful life of 20 to 77 years and metering and other equipment ranges from 5 to 77 years. Depreciation is calculated on a straight-line composite basis over the assets' estimated useful lives. Repair and maintenance costs are expensed as incurred. Costs that are considered a betterment are capitalized. An allowance for funds used during construction, using the rate of return on rate base approved by the Federal Energy Regulatory Commission (FERC), is capitalized and included in the cost of plant, property and equipment. Amounts included in construction work in progress are not amortized until transferred into service.
Impairment of Equity Method Investments	(g) Impairment of Equity Method Investments We review our equity method investments when a significant event or change in circumstances has occurred that may have an adverse effect on the fair value of each investment. When such events or changes occur, we compare the estimated fair value to the carrying value of the related investment. We calculate the estimated fair value of an investment in an equity method investee using an income approach and market approach. The development of fair value estimates requires significant judgment including estimates of future cash flows, which is dependent on internal forecasts, estimates of the long-term rate of growth for the investee, estimates of the useful life over which cash flows will occur, and determination of weighted average cost of capital. The estimates used to calculate the fair value of an investee can change from year to year based on operating results and market conditions. Changes in these estimates and assumptions could materially affect the determination of fair value and our assessment as to whether an investment in an equity method investee has suffered an impairment. If the estimated fair value of an investment is less than its carrying value, we are required to determine if the decline in fair value is other than temporary. This determination considers the aforementioned valuation methodologies, the length of time and the extent to which fair value has been less than carrying value, the financial condition and near-term prospects of the investee, including any specific events which may influence the operations of the investee, the intent and ability of the holder to retain its investment in the investee for a period of time sufficient to allow for any anticipated recovery in market value, and other facts and circumstances. If the fair value of an investment is less than its carrying value and the decline in value is determined to be other than temporary, we record an impairment charge. During the fourth quarter of 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million (See Note 4 for further information).
Impairment of Long-lived Assets	(h) Impairment of Long-lived Assets The Partnership reviews long-lived assets, such as plant, property and equipment for impairment whenever events or changes in circumstances indicate the carrying value may not be recoverable. If the total of the estimated undiscounted future cash flows is less than the carrying value of the assets, an impairment loss is recognized for the excess of the carrying value over the fair value of the assets.
Partners' Equity	(i) Partners' Equity Costs incurred in connection with the issuance of units are deducted from the proceeds received.
Revenue Recognition	(j) Revenue Recognition Transmission revenues are recognized in the period in which the service is provided. When a rate case is pending final FERC approval, a portion of the revenue collected is subject to possible refund. As of December 31, 2015, 2014 and 2013, the Partnership has not recognized any transmission revenue that is subject to possible refund.
Income Taxes	(k) Income Taxes The Partnership is not subject to federal or state income tax. The tax effect of the Partnership's activities accrues to its partners. The Partnership's taxable income or loss, which may vary substantially from the net income or loss reported in the consolidated statement of income, is includable in the federal income tax returns of each partner. The aggregate difference in the basis of the Partnership's net assets for financial and income tax purposes cannot be readily determined because all information regarding each partner's tax attributes related to the partnership is not available.
Acquisitions and Goodwill	(l) Acquisitions and Goodwill The Partnership accounts for business acquisitions from third parties using the acquisition method of accounting and, accordingly, the assets and liabilities of the acquired entities are recorded at their estimated fair values at the date of acquisition. The excess of the purchase price over the fair value of net assets acquired is attributed to goodwill. Goodwill is not amortized and is tested on an annual basis for impairment or more frequently if any indicators of impairment are evident. The Partnership initially assesses qualitative factors to determine whether events or changes in circumstances indicate that the goodwill might be impaired. If the Partnership does not conclude that it is more likely than not that fair value of the reporting unit is greater than its carrying value, the first step of the two-step impairment test is performed by comparing the fair value of the reporting unit to its book value, which includes goodwill. If the fair value is less than book value, an impairment is indicated and a second step is performed to measure the amount of the impairment. In the second step, the implied fair value of goodwill is calculated by deducting the recognized amounts of all tangible and intangible net assets of the reporting unit from the fair value determined in the initial assessment. If the carrying value of goodwill exceeds the calculated implied fair value of goodwill, an impairment charge is recorded. The Partnership accounts for business acquisitions between itself and TransCanada as transactions between entities under common control. Using this approach, the assets and liabilities of the acquired entities are recorded at TransCanada's carrying value. In the event recasting is required, the Partnership's historical financial information will be recast, except net income per common unit, to include the acquired entities for all periods presented. If the fair market value paid for the acquired entities is greater than the recorded net assets of the acquired entities, the excess purchase price paid is recorded as a reduction in Partners' Equity. Similarly, if the fair market value paid for the acquired entities is less than the recorded net assets of the acquired entities, the excess of assets acquired is recorded as an increase in Partners' Equity.
Fair Value Measurements	(m) Fair Value Measurements For cash and cash equivalents, receivables, accounts payable, certain accrued expenses and short-term debt, the carrying amount approximates fair value due to the short maturities of these instruments. For long-term debt instruments and the interest rate swap agreements, fair value is estimated based upon market values (if applicable) or on the current interest rates available to us for debt with similar terms and remaining maturities. Considerable judgment is required in developing these estimates.
Derivative Financial Instruments and Hedging Activities	(n) Derivative Financial Instruments and Hedging Activities The Partnership recognizes all derivative instruments as either assets or liabilities in the balance sheet at their respective fair values. For derivatives designated in hedging relationships, changes in the fair value are either offset through earnings against the change in fair value of the hedged item attributable to the risk being hedged or recognized in accumulated other comprehensive income, to the extent the derivative is effective at offsetting the changes in cash flows being hedged until the hedged item affects earnings. The Partnership only enters into derivative contracts that it intends to designate as a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge). For all hedging relationships, the Partnership formally documents the hedging relationship and its risk management objective and strategy for undertaking the hedge, the hedging instrument, the hedged transaction, the nature of the risk being hedged, how the hedging instrument's effectiveness in offsetting the hedged risk will be assessed prospectively and retrospectively, and a description of the method used to measure ineffectiveness. The Partnership also formally assesses, both at the inception of the hedging relationship and on an ongoing basis, whether the derivatives that are used in hedging relationships are highly effective in offsetting changes in cash flows of hedged transactions. For derivative instruments that are designated and qualify as part of a cash flow hedging relationship, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings. The Partnership discontinues hedge accounting prospectively when it determines that the derivative is no longer effective in offsetting cash flows attributable to the hedged risk, the derivative expires or is sold, terminated, or exercised, the cash flow hedge is de-designated because a forecasted transaction is not probable of occurring, or management determines to remove the designation of the cash flow hedge. In all situations in which hedge accounting is discontinued and the derivative remains outstanding, the Partnership continues to carry the derivative at its fair value on the balance sheet and recognizes any subsequent changes in its fair value in earnings. When it is probable that a forecasted transaction will not occur, the Partnership discontinues hedge accounting and recognizes immediately in earnings gains and losses that were accumulated in other comprehensive income related to the hedging relationship.
Asset Retirement Obligation	(o) Asset Retirement Obligation The Partnership recognizes the fair value of a liability for asset retirement obligations in the period in which it is incurred, when a legal obligation exists and a reasonable estimate of fair value can be made. The fair value is added to the carrying amount of the associated asset and the liability is accreted through charges to operating expenses. The scope and timing of asset retirements related to natural gas pipelines is indeterminable. As a result, the Partnership has recorded no asset retirement obligations as of December 31, 2015 and 2014.
Government Regulation	(p) Government Regulation The Partnership's subsidiaries are subject to regulation by FERC. Under regulatory accounting principles, certain assets or liabilities that result from the regulated ratemaking process may be recorded that would not be recorded under GAAP for non-regulated entities. The timing of recognition of certain revenues and expenses in our regulated business may differ from that otherwise expected under GAAP to appropriately reflect the economic impact of the regulators' decisions regarding revenues and rates. The Partnership regularly evaluates the continued applicability of regulatory accounting, considering such factors as regulatory changes, the impact of competition, and the ability to recover regulatory assets. At December 31, 2015, the Partnership had regulatory assets amounting to $2 million reported as part of accounts receivable and other in the balance sheet representing volumetric fuel tracker assets that are settled with in-kind exchanges with customers continually (2014 – nil). Regulatory liabilities are included in other long-term liabilities (refer to Note 8). Allowance for funds used during construction is capitalized and included in plant, property and equipment.
Debt Issuance Costs	(q) Debt Issuance Costs Costs related to the issuance of debt are deferred and amortized using the effective interest rate method over the term of the related debt.

ORGANIZATION (Tables)

12 Months Ended

Dec. 31, 2015

ORGANIZATION

Pipeline	Length	Description	Ownership

Gas Transmission Northwest LLC (GTN)	1,377 miles	Extends between an interconnection near Kingsgate, British Columbia, Canada at the Canadian border to a point near Malin, Oregon at the California border and delivers natural gas to the Pacific Northwest and to California.	100 percent
Northern Border Pipeline Company (Northern Border)	1,408 miles	Extends between the Canadian border near Port of Morgan, Montana to a terminus near North Hayden, Indiana, south of Chicago. Northern Border is capable of receiving natural gas from Canada, the Williston Basin and Rocky Mountain area for deliveries to the Midwest. ONEOK Partners, L.P. owns the remaining 50 percent of Northern Border.	50 percent
Bison Pipeline LLC (Bison)	303 miles	Extends from a location near Gillette, Wyoming to Northern Border's pipeline system in North Dakota. Bison transports natural gas from the Powder River Basin to Midwest markets.	100 percent
Great Lakes Gas Transmission Limited Partnership (Great Lakes)	2,115 miles	Connects with the TransCanada Mainline at the Canadian border near Emerson, Manitoba, Canada and St. Clair, Michigan, near Detroit. Great Lakes is a bi-directional pipeline that can receive and deliver natural gas at multiple points along its system. TransCanada owns the remaining 53.55 percent of Great Lakes.	46.45 percent
North Baja Pipeline, LLC (North Baja)	86 miles	Extends between an interconnection with the El Paso Natural Gas Company pipeline near Ehrenberg, Arizona and an interconnection with a natural gas pipeline near Ogilby, California on the Mexican border transporting natural gas in the southwest. North Baja is a bi-directional pipeline.	100 percent
Tuscarora Gas Transmission Company (Tuscarora)	305 miles	Extends between the GTN pipeline near Malin, Oregon to its terminus near Reno, Nevada and delivers natural gas in northeastern California and northwestern Nevada.	100 percent
Portland Natural Gas Transmission System (PNGTS)	295 miles	Connects with the TransQuebec and Maritimes Pipeline (TQM) at the Canadian border to deliver natural gas to customers in the U.S. northeast. TransCanada owns 11.81 percent of PNGTS. Northern New England Investment Company, Inc. owns the remaining 38.29 percent of PNGTS.	49.9 percent(a)


(a)	Effective January 1, 2016 (Refer to Note 22)

INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of equity investees and summarized financial information for equity investees

		Equity Earnings from Unconsolidated Affiliates(b)			Investment in Unconsolidated Affiliates
		Year ended December 31			December 31
	Ownership Interest at December 31, 2015	Year ended December 31			December 31
(millions of dollars)	Ownership Interest at December 31, 2015	2015	2014	2013	2015		2014

Northern Border(a)	50%	66	69	64	480		505
Great Lakes	46.45%	31	19	3	485	(c)	672

		97	88	67	965		1,177


(a)	Equity earnings from Northern Border is net of the 12-year amortization of a $10 million transaction fee paid to the operator of Northern Border at the time of the Partnership's additional 20 percent acquisition in April 2006.
(b)	Equity Earnings represents our share in investee's earnings and does not include any impairment charge on the equity method investment recorded as a reduction of carrying value of these investments.
(c)	During the fourth quarter of 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million. See discussion below.

Schedule of equity investees and summarized financial information for equity investees

December 31 (millions of dollars)		2015		2014

Assets
Cash and cash equivalents		27		41
Other current assets		33		34
Plant, property and equipment, net		1,124		1,163
Other assets		18		34

		1,202		1,272

Liabilities and Partners' Equity
Current liabilities		39		64
Deferred credits and other		26		22
Long-term debt, including current maturities		411		411
Partners' equity
	Partners' capital	728		777
	Accumulated other comprehensive loss	(2	)	(2	)

		1,202		1,272

Year ended December 31 (millions of dollars)	2015		2014		2013

Transmission revenues	286		293		286
Operating expenses	(70	)	(72	)	(75	)
Depreciation	(60	)	(59	)	(58	)
Financial charges and other	(22	)	(22	)	(23	)

Net income	134		140		130

Schedule of equity investees and summarized financial information for equity investees

December 31 (millions of dollars)	2015	2014

Assets
Current assets	86	66
Plant, property and equipment, net	727	748

	813	814

Liabilities and Partners' Equity
Current liabilities	31	38
Long-term debt, including current maturities	297	316
Partners' equity	485	460

	813	814

Year ended December 31 (millions of dollars)	2015		2014		2013

Transmission revenues	177		146		124
Operating expenses	(59	)	(53	)	(60)
Depreciation	(28	)	(28	)	(31)
Financial charges and other	(23	)	(25	)	(27)

Net income	67		40		6

PLANT, PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2015

PLANT, PROPERTY AND EQUIPMENT

Schedule of plant, property and equipment

	2015				2014
December 31 (millions of dollars)	Cost	Accumulated Depreciation		Net Book Value	Cost	Accumulated Depreciation		Net Book Value

Pipeline	2,086	(638	)	1,448	2,038	(574	)	1,464
Compression	516	(134	)	382	514	(126	)	388
Metering and other	156	(39	)	117	145	(37	)	108
Construction in progress	2	–		2	8	–		8

	2,760	(811	)	1,949	2,705	(737	)	1,968

ACQUISITIONS (Tables)

12 Months Ended

Dec. 31, 2015

Schedule of purchase price

(millions of dollars)

Net Purchase Price(a)		359
Less: TransCanada's carrying value of non-controlling interest at April 1, 2015		232

Excess purchase price(b)		127


(a)	Total purchase price of $457 million less the assumption of $98 million of proportional GTN debt by the Partnership.
(b)	The excess purchase price of $127 million was recorded as a reduction in Partners' Equity.

Bison

Schedule of purchase price

(millions of dollars)

Total cash consideration		217
TransCanada's carrying value of non-controlling interest at October 1, 2014		188

Excess purchase price		29

GTN and Bison

Schedule of purchase price

(millions of dollars)

Current assets	67
Property, plant and equipment, net	1,792
Other assets	1
Current liabilities	(20	)
Other liabilities	(21	)
Long-term debt	(325	)

	1,494
Non-controlling interest	(448	)
Carrying value of pre-existing 25% interest in each of GTN and Bison	(374	)

Carrying value of acquired 45% interest in each of GTN and Bison	672
Excess purchase price over net assets acquired (includes Carty Lateral consideration)	274

Total cash consideration including $25 million Carty Lateral consideration	946

DEBT AND CREDIT FACILITIES (Tables)

12 Months Ended

Dec. 31, 2015

DEBT AND CREDIT FACILITIES

Schedule of debt and credit facilities

December 31 (millions of dollars)	2015	2014

Senior Credit Facility due 2017	200	330
2013 Term Loan Facility due 2018	500	500
Short-Term Loan Facility due 2015	–	170
2015 Term Loan Facility due 2018	170	–
4.65% Unsecured Senior Notes due 2021, net of discount (2015 and 2014 – nil)	350	350
4.375% Unsecured Senior Notes due 2025, net of $1 million discount	349	–
5.09% Unsecured Senior Notes due 2015	–	75
5.29% Unsecured Senior Notes due 2020	100	100
5.69% Unsecured Senior Notes due 2035	150	150
Unsecured Term Loan Facility due 2019	75	–
3.82% Series D Senior Notes due 2017	16	20

	1,910	1,695
Less: current portion	14	249

	1,896	1,446

Schedule of principal repayments required on debt

(millions of dollars)

2016		14
2017		222
2018		690
2019		35
2020		100
Thereafter		849

		1,910

OTHER LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2015

OTHER LIABILITIES

Schedule of other liabilities

December 31 (millions of dollars)	2015	2014

Regulatory liabilities	24	23
Other liabilities	3	3

	27	26

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)

12 Months Ended

Dec. 31, 2015

ACCUMULATED OTHER COMPREHENSIVE LOSS

Schedule of changes in accumulated other comprehensive loss (AOCL) by components

(millions of dollars)		Cash flow hedges

Balance at December 31, 2012		(1)
Other comprehensive loss before reclassifications		–
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance at December 31, 2013		(1)
Other comprehensive loss before reclassifications		(1)
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance at December 31, 2014		(2)
Other comprehensive loss before reclassifications		–
Amounts reclassified from AOCL		–

Net other comprehensive loss		–

Balance as of December 31, 2015		(2)

FINANCIAL CHARGES AND OTHER (Tables)

12 Months Ended

Dec. 31, 2015

FINANCIAL CHARGES AND OTHER

Schedule of components of financial charges and other

Year ended December 31 (millions of dollars)	2015		2014		2013(a)

Interest expense	58		48		42
Amortization of debt issue costs	1		1		1
Net realized loss related to the interest rate swaps and options	2		2		1
Other	(5	)	(1	)	–

	56		50		44


(a)	Recast as discussed in Note 2 and Note 6.

NET INCOME (LOSS) PER COMMON UNIT (Tables)

12 Months Ended

Dec. 31, 2015

NET INCOME (LOSS) PER COMMON UNIT

Schedule of net income (loss) per common unit

(millions of dollars, except per common unit amounts)	2015		2014	2013(a)

Net income allocable to controlling interests	13		172	155
Net income attributable to GTN's and Bison's former parent	–		–	26	(b)

Net income allocable to General and Limited Partners(b)	13		172	129
Incentive distributions attributable to the General Partner(c)	3		1	–
Net income attributable to the Class B units(d)	12		–	–

Net income (loss) allocable to the General Partner and common units	(2	)	171	129
Net Income (loss) allocable to the General Partner's two percent interest	–		3	3

Net income (loss) attributable to common units	(2	)	168	126

Weighted average common units outstanding (millions) – basic and diluted	63.9		62.7	58.9
Net income (loss) per common unit – basic and diluted	$ (0.03	)	$ 2.67	$ 2.13


(a)	Recast as discussed in Note 2 and Note 6.
(b)	Net income allocable to General and Limited Partners excludes net income attributed to GTN's and Bison's former parent as it was allocated to TransCanada and was not allocable to either the general partner, common units or Class B units (refer to Note 6 – 2013 Acquisition).
(c)	Net income allocable to General and Limited Partners is allocated based on their respective participation rights, after giving effect to any priority income allocation for incentive distributions that are allocated 100 percent to the General Partner. Under the terms of the Partnership Agreement, for any quarterly period, the participation of the IDRs is limited to the available cash distributions declared. Accordingly, incentive distributions allocated to the General Partner was based from the Partnership's available cash during the current reporting period, but declared and paid in the subsequent reporting period.
(d)	As discussed in Notes 6 and 9, the Class B units entitle TransCanada to a distribution which is an amount based on 30 percent of GTN's distributions after achieving certain annual thresholds. The distribution will be payable in the first quarter with respect to the prior year's distributions. Consistent with the application of Accounting Standards Codification (ASC) Topic 260 – "Earnings per share," the Partnership allocated a portion of net income attributable to controlling interests to the Class B units upon 30 percent of GTN's total distributable cash flows exceeding $15 million for the nine month period ended December 31, 2015. During the nine months ended December 31, 2015, 30 percent of GTN's total distributable cash flow was $27 million. As a result, $12 million of net income attributable to controlling interests was allocated to the Class B units in 2015. On February 12, 2016, this amount was paid to TransCanada (Refer to Note 13 and 22).

CASH DISTRIBUTIONS (Tables)

12 Months Ended

Dec. 31, 2015

CASH DISTRIBUTIONS

Schedule of allocations of available cash from operating surplus between common unitholders and General Partner

		Marginal Percentage Interest in Distribution
	Total Quarterly Distribution Per Unit Target Amount	Common Unitholders	General Partner

Minimum Quarterly Distribution	$0.45	98%	2%
First Target Distribution	above $0.45 up to $0.81	98%	2%
Second Target Distribution	above $0.81 up to $0.88	85%	15%
Thereafter	above $0.88	75%	25%

Schedule of distributions

The following table provides information about our distributions (in millions, except per unit distributions amounts).

					Limited Partners			General Partner
Declaration Date		Payment Date		Per Unit Distribution	Common Units	Class B Units(c)		2%	IDRs(a)	Total Cash Distribution

1/17/2013		2/14/2013		$ 0.78	$ 42	$–		$ 1	$–	$ 43
4/23/2013		5/15/2013		$ 0.78	$ 42	$–		$ 1	$–	$ 43
7/23/2013		8/14/2013		$ 0.81	$ 50	$–		$ 1	$–	$ 51
10/24/2013		11/14/2013		$ 0.81	$ 50	$–		$ 1	$–	$ 51
1/16/2014		2/14/2014		$ 0.81	$ 50	$–		$ 1	$–	$ 51
4/25/2014		5/15/2014		$ 0.81	$ 51	$–		$ 1	$–	$ 52
7/23/2014		8/14/2014		$ 0.84	$ 53	$–		$ 1	$–	$ 54
10/23/2014		11/14/2014		$ 0.84	$ 53	$–		$ 1	$ 1	$ 55
1/22/2015		2/13/2015		$ 0.84	$ 54	$–		$ 1	$–	$ 55
4/23/2015		5/15/2015		$ 0.84	$ 54	$–		$ 1	$–	$ 55
7/23/2015		8/14/2015		$ 0.89	$ 56	$–		$ 2	$ 1	$ 59
10/22/2015		11/13/2015		$ 0.89	$ 57	$–		$ 1	$ 1	$ 59
1/21/2016	(b)	2/12/2016	(b)	$ 0.89	$ 57	$ 12	(d)	$ 1	$ 1	$ 71


(a)	The distributions paid for the year ended December 31, 2015 included incentive distributions to the General Partner of $2 million (2014 – $1 million). There were no incentive distributions paid to the General Partner in the year ended December 31, 2013.
(b)	On February 12, 2016, we paid a cash distribution of $0.89 per unit on our outstanding common units to unitholders of record at the close of business on February 2, 2016 (refer to Note 22).
(c)	The Class B units issued by us on April 1, 2015 represent limited partner interests in us and entitle TransCanada to an annual distribution which is an amount based on 30 percent of GTN's annual distributions after achieving certain annual thresholds (refer to Note 6 and 9).
(d)	On February 12, 2016, we paid TransCanada $12 million representing 30 percent of GTN's total distributable cash flows for the nine months ended December 31, 2015 less $15 million (refer to Note 9 and 22).

CHANGE IN OPERATING WORKING CAPITAL (Tables)

12 Months Ended

Dec. 31, 2015

CHANGE IN OPERATING WORKING CAPITAL

Schedule of change in operating working capital

Year Ended December 31 (millions of dollars)	2015		2014(a)	2013(a)

Change in accounts receivable and other	–		2	1
Change in accounts payable and accrued liabilities	(3)		4	(9	)
Change in accounts payable to affiliates	(10)	(b)	11	(2	)
Change in accrued interest	4		–	2

Change in operating working capital	(9)		17	(8	)


(a)	Recast as discussed in Note 2 and Note 6.
(b)	Excludes certain non-cash items primarily related to accruals of $10 million for construction of GTN's Carty Lateral and $2 million for costs related to acquisition of 49.9 percent interest in PNGTS (Note 22).

TRANSACTIONS WITH MAJOR CUSTOMERS (Tables)

12 Months Ended

Dec. 31, 2015

TRANSACTIONS WITH MAJOR CUSTOMERS

Schedule of revenues from major customers

Year Ended December 31 (millions of dollars)	2015	2014	2013(a)

Anadarko Energy Services Company (Anadarko)	48	48	48
Pacific Gas and Electric Company (Pacific Gas)	42	45	46


(a)	Recast as discussed in Note 2 and Note 6.

RELATED PARTY TRANSACTIONS (Tables)

12 Months Ended

Dec. 31, 2015

RELATED PARTY TRANSACTIONS

Summary of capital and operating costs charged to pipeline systems by related party

Year ended December 31 (millions of dollars)		2015	2014	2013

Capital and operating costs charged by TransCanada's subsidiaries to:
	GTN(a)(b)	30	30	28
	Northern Border(a)	36	35	30
	Bison(a)(b)(d)	4	6	5
	Great Lakes(a)	30	30	31
	North Baja	5	5	4
	Tuscarora	4	4	4
Impact on the Partnership's net income attributable to controlling interests:
	GTN(b)(c)	25	19	19
	Northern Border	14	16	14
	Bison(b)(d)	4	4	4
	Great Lakes	13	13	14
	North Baja	5	4	4
	Tuscarora	4	4	4

Summary of amount payable to related party for costs charged

December 31 (millions of dollars)		2015	2014

Amount payable to TransCanada's subsidiaries for costs charged in the year by:
	GTN(a)	3	10
	Northern Border(a)	5	10
	Bison(a)	–	2
	Great Lakes(a)	3	9
	North Baja	–	1
	Tuscarora	1	1


(a)	Represents 100 percent of the costs.
(b)	Recast as discussed in Note 2 and Note 6.
(c)	In 2015, the Partnership acquired remaining 30 percent interest in GTN (Refer to Note 6).
(d)	In 2014, the Partnership acquired remaining 30 percent interest in Bison (Refer to Note 6).

QUARTERLY FINANCIAL DATA (unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

QUARTERLY FINANCIAL DATA (unaudited)

Schedule of selected unaudited financial data

Quarter ended (millions of dollars except per common unit amounts)	Mar 31	Jun 30	Sept 30	Dec 31

2015
Transmission revenues	87	85	83	89
Equity earnings(a)	31	15	17	34
Impairment of equity-method investment(b)	–	–	–	(199)
Net income (loss)	64	44	49	(137)
Net income (loss) attributable to controlling interests	57	44	49	(137)
Net income (loss) per common unit	$ 0.88	$ 0.66	$ 0.70	(2.24)
Cash distribution paid	55	55	59	59

2014
Transmission revenues	87	82	80	87
Equity earnings(a)	33	18	15	22
Net income	67	45	39	53
Net income attributable to controlling interests	57	37	31	47
Net income per common unit	$ 0.90	$ 0.58	$ 0.48	$ 0.71
Cash distributions paid	51	52	54	55


(a)	Equity Earnings represents our share in investee's earnings and does not include any impairment charge on equity method goodwill included as part of the carrying value of our investments in unconsolidated affiliates.
(b)	During the three months ended December 31, 2015, we recognized an impairment charge on our investment in Great Lakes amounting to $199 million. No impairment has been identified on our investment in Northern Border (Refer to Note 4).

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2015

FAIR VALUE MEASUREMENTS

Schedule of estimated fair value of debt

	2015		2014
December 31 (millions of dollars)	Carrying Value	Fair Value	Carrying Value	Fair Value

Senior Credit Facility due 2017	200	200	330	330
2013 Term Loan Facility due 2018	500	500	500	500
Short-Term Loan Facility due 2015	–	–	170	170
2015 Term Loan Facility due 2018	170	170	–	–
4.65% Unsecured Senior Notes due 2021	350	338	350	375
4.375% Unsecured Senior Notes due 2025	349	314	–	–
5.09% Unsecured Senior Notes due 2015	–	–	75	76
5.29% Unsecured Senior Notes due 2020	100	108	100	111
5.69% Unsecured Senior Notes due 2035	150	151	150	168
Unsecured Term Loan Facility due 2019	75	75	–	–
3.82% Series D Senior Notes due 2017	16	17	20	21

	1,910	1,873	1,695	1,751

ACCOUNTS RECEIVABLE AND OTHER (Tables)

12 Months Ended

Dec. 31, 2015

ACCOUNTS RECEIVABLE AND OTHER

Schedule of accounts receivable and other

December 31 (millions of dollars)	2015	2014

Trade accounts receivable, net of allowance of nil	31	30
Accounts receivable from affiliates	–	1
Other	4	4

	35	35

ORGANIZATION - Ownership Interests in Natural Gas Pipeline Systems of Subsidiaries and Equity Method Investments (Details) - mi		12 Months Ended
	Jan. 01, 2016	Dec. 31, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2013	Feb. 28, 2007
GTN
Organization
Ownership interest (as a percent)		100.00%
Northern Border
Organization
Ownership interest (as a percent)		50.00%
Bison
Organization
Ownership interest (as a percent)		100.00%
Great Lakes
Organization
Ownership interest (as a percent)		46.45%	46.45%			46.45%
North Baja Pipeline, LLC
Organization
Ownership interest (as a percent)		100.00%
Tuscarora Gas Transmission Company
Organization
Ownership interest (as a percent)		100.00%
TransCanada \| GTN
Organization
Remaining noncontrolling ownership interest (as a percent)			30.00%
TransCanada \| Bison
Organization
Remaining noncontrolling ownership interest (as a percent)				30.00%
GTN
Organization
Length of pipeline owned (in miles)		1,377
Northern Border
Organization
Length of pipeline owned (in miles)		1,408
Bison
Organization
Length of pipeline owned (in miles)		303
Great Lakes
Organization
Length of pipeline owned (in miles)		2,115
North Baja Pipeline, LLC
Organization
Length of pipeline owned (in miles)		86
Tuscarora Gas Transmission Company
Organization
Length of pipeline owned (in miles)		305
Portland Natural Gas Transmission System
Organization
Length of pipeline owned (in miles)		295
TransCanada \| Bison
Organization
Remaining ownership interest (as a percent)					75.00%
TransCanada \| Great Lakes
Organization
Remaining ownership interest (as a percent)		53.55%
ONEOK Partners, L.P. \| Northern Border
Organization
Remaining ownership interest (as a percent)		50.00%
Subsequent event \| Portland Natural Gas Transmission System
Organization
Ownership interest (as a percent)	49.90%
Subsequent event \| TransCanada \| Portland Natural Gas Transmission System
Organization
Remaining noncontrolling ownership interest (as a percent)	11.81%
Subsequent event \| North New England Investment \| Portland Natural Gas Transmission System
Organization
Remaining noncontrolling ownership interest (as a percent)	38.29%

ORGANIZATION - Capitalization (Details 2) - shares

12 Months Ended

Apr. 01, 2015

May 22, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

General Partner | TC PipeLines GP, Inc.

64,300,000

63,600,000

62,300,000

^[1]

IDRs ownership (as a percent)

100.00%

Ownership interest in the Partnership (as a percent)

2.00%

Limited Partners | Common units

Limited Partners | Common units | TC PipeLines GP, Inc.

64,317,449

Limited Partners | Common units | TransCanada

5,797,106

Limited partner interest (as a percent)

11,287,725

26.60%

Limited Partners | Class B units | TransCanada

Limited partner interest (as a percent)

1,900,000

100.00%

[1]	Recast as discussed in Note 2 and Note 6.

SIGNIFICANT ACCOUNTING POLICIES - Ownership Interests Acquired (Details)	Apr. 01, 2015	Mar. 31, 2015	Oct. 01, 2014	Sep. 30, 2014	Jul. 01, 2013
TransCanada \| GTN
Acquisitions
Remaining noncontrolling ownership interest (as a percent)		30.00%
TransCanada \| Bison
Acquisitions
Remaining noncontrolling ownership interest (as a percent)				30.00%
GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Acquisitions
Interest acquired (as a percent)	30.00%				45.00%
Ownership interest, including acquired interest (as a percent)					70.00%
Bison \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Acquisitions
Interest acquired (as a percent)			30.00%		45.00%
Ownership interest, including acquired interest (as a percent)					70.00%

SIGNIFICANT ACCOUNTING POLICIES - Useful Lives of Plant, Property and Equipment (Details 2)	12 Months Ended
	Dec. 31, 2015
Pipeline facilities and compression equipment \| Minimum
PLANT, PROPERTY AND EQUIPMENT
Estimated useful lives	20 years
Pipeline facilities and compression equipment \| Maximum
PLANT, PROPERTY AND EQUIPMENT
Estimated useful lives	77 years
Metering and other \| Minimum
PLANT, PROPERTY AND EQUIPMENT
Estimated useful lives	5 years
Metering and other \| Maximum
PLANT, PROPERTY AND EQUIPMENT
Estimated useful lives	77 years

SIGNIFICANT ACCOUNTING POLICIES - Impairment of Equity Method Investments (Details 3) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015
Investments in unconsolidated affiliates
Impairment charge recognized on equity method investment	$ 199	$ 199
Great Lakes \| Nonrecurring fair value measurement
Investments in unconsolidated affiliates
Impairment charge recognized on equity method investment	$ 199

SIGNIFICANT ACCOUNTING POLICIES - Asset Retirement Obligation and Regulatory Assets (Details 4) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Accounts receivable and other
Regulatory assets and liabilities
Regulatory assets	$ 2,000,000	$ 0
Pipeline
Asset Retirement Obligation
Asset retirement liabilities	$ 0	$ 0

INVESTMENTS IN UNCONSOLIDATED AFFILIATES (Details) - USD ($)
$ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

Dec. 31, 2015

Nov. 14, 2013

Apr. 30, 2006

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Feb. 28, 2007

Equity Earnings from Unconsolidated Affiliates

$ 34

$ 17

$ 15

$ 31

$ 22

$ 15

$ 18

$ 33

$ 97

$ 88

$ 67

^[1]

Investment in Unconsolidated Affiliates

$ 965

965

1,177

965

1,177

Impairment charge recognized on equity method investment

199

$ 199

Increase in transportation rates compared to current rates (as a percent)

21.00%

Total cash call issued to fund debt repayment

$ 10

$ 9

Equity Earnings from Unconsolidated Affiliates

50.00%

$ 66

Investment in Unconsolidated Affiliates

$ 480

505

480

505

Amortization period of transaction fee

12 years

Transaction fee

$ 10

Additional ownership interest acquired (as a percent)

20.00%

Undistributed earnings

Equity contribution

^[1]

Amount of difference between the carrying value and the underlying equity in net assets resulting from the recognition and inclusion of goodwill

117

Assets

Cash and cash equivalents

Other current assets

Plant, property and equipment, net

1,124

1,163

1,124

1,163

Other assets

Assets, total

1,202

1,272

1,202

1,272

LIABILITIES AND PARTNERS' EQUITY

Current liabilities

Deferred credits and other

Long-term debt, including current maturities

411

Partners' equity

Partners' equity

728

777

728

777

Accumulated other comprehensive loss

(2)

Liabilities and Partners' Equity, total

1,202

$ 1,202

1,272

1,202

1,272

Revenues (expenses)

286

293

286

Operating expenses

(70)

(72)

(75)

Financial charges and other

(60)

(59)

(58)

(22)

(23)

Northern Border | Nonrecurring fair value measurement

$ 134

140

130

Impairment charge recognized on equity method investment

$ 0

Northern Border | ONEOK Partners, L.P.

50.00%

Equity Earnings from Unconsolidated Affiliates

46.45%

$ 31

Investment in Unconsolidated Affiliates

$ 485

672

485

672

Undistributed earnings

Equity contribution

$ 4

^[1]

Amount of difference between the carrying value and the underlying equity in net assets resulting from the recognition and inclusion of goodwill

260

458

260

458

Assets

Current assets

Plant, property and equipment, net

727

748

727

748

Assets, total

813

814

813

814

LIABILITIES AND PARTNERS' EQUITY

Current liabilities

Long-term debt, including current maturities

297

316

297

316

Partners' equity

Partners' equity

485

460

485

460

Liabilities and Partners' Equity, total

$ 813

813

$ 814

813

814

Revenues (expenses)

177

146

124

Operating expenses

(59)

(53)

(60)

Financial charges and other

(28)

(31)

(23)

(25)

(27)

Great Lakes | Nonrecurring fair value measurement

$ 67

$ 40

$ 6

Impairment charge recognized on equity method investment

$ 199

Great Lakes | TransCanada

Great Lakes | Level 3 | Nonrecurring fair value measurement

53.55%

TC PipeLines Intermediate Limited Partnership

Fair value of investment

$ 465

Partnership interest held (as a percent)

98.9899%

TC GL Intermediate Limited Partnership

Partnership interest held (as a percent)

98.9899%

[1]	Recast as discussed in Note 2 and Note 6.

PLANT, PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
PLANT, PROPERTY AND EQUIPMENT
Cost	$ 2,760	$ 2,705
Accumulated Depreciation	(811)	(737)
Net Book Value	1,949	1,968
Pipeline
PLANT, PROPERTY AND EQUIPMENT
Cost	2,086	2,038
Accumulated Depreciation	(638)	(574)
Net Book Value	1,448	1,464
Compression
PLANT, PROPERTY AND EQUIPMENT
Cost	516	514
Accumulated Depreciation	(134)	(126)
Net Book Value	382	388
Metering and other
PLANT, PROPERTY AND EQUIPMENT
Cost	156	145
Accumulated Depreciation	(39)	(37)
Net Book Value	117	108
Construction in progress
PLANT, PROPERTY AND EQUIPMENT
Cost	2	8
Net Book Value	$ 2	$ 8

ACQUISITIONS - 2015 GTN Acquisition Summary and Terms of New Class B Units (Details) - USD ($)			9 Months Ended	12 Months Ended
	Apr. 01, 2015	Jul. 01, 2013	Dec. 31, 2015	Dec. 31, 2015	Mar. 31, 2015
TransCanada \| GTN
Noncontrolling interest
Remaining noncontrolling ownership interest (as a percent)					30.00%
GTN
Acquisition
Total cash consideration				$ 264,000,000
GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Acquisition
Interest acquired (as a percent)	30.00%	45.00%
Purchase price adjustments	$ 11,000,000
Purchase price	457,000,000	$ 750,000,000
Total cash consideration	264,000,000
Assumption of proportional debt	98,000,000	$ 146,000,000
GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| As previously recast
Acquisition
Purchase price	$ 446,000,000
Partnership interest \| Class B units \| GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Acquisition
Units issued (in units)	1,900,000
Value per unit (in dollars per unit)	$ 50
Equity issuance	$ 95,000,000
GTN \| Class B units \| TransCanada \| Distributions
Distributions
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)	30.00%
Percentage applied to 30 percent of GTN's distributions above threshold through March 31, 2020	100.00%
Threshold of 30 percent of GTN's annual distributions for payment to Class B units at specified percentage	$ 20,000,000
Percentage applied to 30 percent of GTN's distributions above threshold after March 31, 2020	25.00%
Percentage applied to GTN's distributable cash flow for the nine months ending December 31, 2015			30.00%
Prorated threshold of GTN's distributions for payment to Class B units			$ 15,000,000

ACQUISITIONS - Net Purchase Price Allocation for 2015 GTN Acquisition (Details 2) - USD ($) $ in Millions				12 Months Ended
	Apr. 01, 2015	Jul. 01, 2013	May 22, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net purchase price allocation
Equity contribution				$ 2
General Partner
Net purchase price allocation
Equity contribution	$ 2			2
GTN
Net purchase price allocation
Reduction in Partners' Equity				359
GTN \| General Partner
Net purchase price allocation
Reduction in Partners' Equity				$ 3
GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Net purchase price allocation
Net Purchase Price	359
Less: TransCanada's carrying value of non-controlling interest	232
Excess purchase price	127	$ 262
Purchase price	457	750
Assumption of proportional debt	98	$ 146
GTN \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| Common units and General Partner interest combined
Net purchase price allocation
Reduction in Partners' Equity	$ 127
TC PipeLines GP, Inc. \| General Partner
Net purchase price allocation
Ownership interest in the Partnership (as a percent)	2.00%		2.00%	2.00%	2.00%	2.00%

ACQUISITIONS - 2014 Bison Acquisition (Details 3) - USD ($) $ in Millions			12 Months Ended
	Oct. 01, 2014	Jul. 01, 2013	Dec. 31, 2014	Sep. 30, 2014
Bison
Acquisitions
Total cash consideration			$ 217
Reduction in Partners' Equity			217
Bison \| Limited Partners \| Common units
Acquisitions
Reduction in Partners' Equity			$ 29
Bison \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Acquisitions
Interest acquired by Partnership (as a percent)	30.00%	45.00%
Purchase price		$ 300
Purchase price adjustments	$ 2
Total cash consideration	217
TransCanada's carrying value of non-controlling interest	188
Excess purchase price	29	$ 12
Bison \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| As previously recast
Acquisitions
Purchase price	215
Bison \| Former parent, TransCanada subsidiaries \| Limited Partners \| Transaction between entities under common control \| Common units
Acquisitions
Reduction in Partners' Equity	$ 29
Bison \| TransCanada
Acquisitions
Remaining noncontrolling ownership interest (as a percent)				30.00%

ACQUISITIONS - 2013 Acquisition of GTN and Bison (Details 4) - USD ($)

12 Months Ended

Apr. 01, 2015

Oct. 01, 2014

Jul. 02, 2013

Jul. 01, 2013

May 22, 2013

Apr. 11, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Jun. 30, 2013

Cash paid

$ 25,000,000

$ 921,000,000

^[1]

$ 2,000,000

General Partner

Common units | Equity Issuance, May 2013

$ 2,000,000

Units sold in public offering

8,855,000

Price per common unit in public offering

$ 43.85

Net proceeds from issuance of common units

$ 373,000,000

2013 Term Loan Facility due 2018

Borrowings under the facility

$ 500,000,000

Senior Credit Facility due 2017 | Senior revolving credit facility

Maximum borrowing capacity

$ 500,000,000

TC PipeLines GP, Inc. | General Partner

Ownership interest in the Partnership (as a percent)

2.00%

TC PipeLines GP, Inc. | Equity Issuance, May 2013 | General Partner

$ 8,000,000

GTN and Bison

GTN and Bison | General Partner

$ (274,000,000)

GTN and Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control

(6,000,000)

Working capital adjustments

17,000,000

Cash paid

921,000,000

Property, plant and equipment, net

Current assets

67,000,000

1,792,000,000

1,000,000

(20,000,000)

(21,000,000)

(325,000,000)

1,494,000,000

Carrying value of acquired 45% interest in each of GTN and Bison

672,000,000

Excess purchase price over net assets acquired (includes Carty Lateral consideration)

274,000,000

Total cash consideration including $25 million Carty Lateral consideration

946,000,000

Increase in the net income attributable to common units resulting from retrospective consolidation

$ 26,000,000

GTN and Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control | As previously recast

GTN and Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control | Carrying value

1,050,000,000

Carrying value of pre-existing 25% interest in each of GTN and Bison

Non-controlling interest

(448,000,000)

(374,000,000)

GTN and Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control | Common units and General Partner interest combined

$ (274,000,000)

$ (359,000,000)

GTN | General Partner

GTN | Former parent, TransCanada subsidiaries | Transaction between entities under common control

$ (3,000,000)

Interest acquired by Partnership (as a percent)

30.00%

45.00%

Ownership interest, including acquired interest (as a percent)

70.00%

Working capital adjustments

$ 457,000,000

$ 750,000,000

11,000,000

Acquired debt

98,000,000

146,000,000

Contingent additional payment, maximum

25,000,000

Additional acquisition consideration relating to Carty Lateral project

$ 25,000,000

Excess purchase price over net assets acquired (includes Carty Lateral consideration)

127,000,000

$ 262,000,000

Pre-existing interest acquired by the partnership (as a percent)

25.00%

GTN | Former parent, TransCanada subsidiaries | Transaction between entities under common control | As previously recast

GTN | Former parent, TransCanada subsidiaries | Transaction between entities under common control | Common units and General Partner interest combined

446,000,000

$ (127,000,000)

Bison

Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control

$ (217,000,000)

Interest acquired by Partnership (as a percent)

30.00%

45.00%

Ownership interest, including acquired interest (as a percent)

70.00%

Working capital adjustments

$ 300,000,000

$ 2,000,000

Excess purchase price over net assets acquired (includes Carty Lateral consideration)

29,000,000

$ 12,000,000

Pre-existing interest acquired by the partnership (as a percent)

25.00%

Bison | Former parent, TransCanada subsidiaries | Transaction between entities under common control | As previously recast

Credit facilities, short-term loan facility and long-term debt

$ 215,000,000

[1]	Recast as discussed in Note 2 and Note 6.

DEBT AND CREDIT FACILITIES - Amounts Outstanding and Description of Terms (Details) - USD ($)

3 Months Ended

12 Months Ended

Sep. 30, 2015

Mar. 13, 2015

Jul. 02, 2013

Jul. 01, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Jun. 01, 2015

Apr. 01, 2015

Total credit facilities, short-term loan facility and long-term debt

$ 1,910,000,000

Short-term loan

$ 170,000,000

1,910,000,000

1,695,000,000

Less: current portion

14,000,000

249,000,000

Long-term debt

$ 1,896,000,000

1,896,000,000

1,446,000,000

Amount borrowed

$ 618,000,000

35,000,000

$ 937,000,000

^[1]

GTN | Former parent, TransCanada subsidiaries | Transaction between entities under common control

Credit facilities, short-term loan facility and long-term debt

Interest acquired by Partnership (as a percent)

45.00%

30.00%

2013 Term Loan Facility due 2018

Credit facilities, short-term loan facility and long-term debt

Borrowings under the facility

$ 500,000,000

Senior Credit Facility and the Term Loan Facilities due in 2018

Credit facilities, short-term loan facility and long-term debt

Leverage ratio, actual (as a percent)

4.68%

Senior Credit Facility and the Term Loan Facilities due in 2018 | Maximum

Credit facilities, short-term loan facility and long-term debt

Leverage ratio, covenant (as a percent)

550.00%

Senior Credit Facility and the Term Loan Facilities due in 2018 | Debt agreement covenants, initial period after occurrence of acquisition

Credit facilities, short-term loan facility and long-term debt

Additional period immediately following the fiscal quarter in which a specified material acquisition occurs

6 months

Senior Credit Facility and the Term Loan Facilities due in 2018 | Debt agreement covenants, initial period after occurrence of acquisition | Maximum

Credit facilities, short-term loan facility and long-term debt

Leverage ratio, covenant (as a percent)

550.00%

Senior Credit Facility and the Term Loan Facilities due in 2018 | Debt agreement covenants, periods subsequent to initial period after occurrence of acquisition | Maximum

Credit facilities, short-term loan facility and long-term debt

Leverage ratio, covenant (as a percent)

500.00%

Term loan | Short-Term Loan Facility due 2015

Credit facilities, short-term loan facility and long-term debt

Short-term loan

170,000,000

Revolving credit facility | Senior Credit Facility due 2017

Credit facilities, short-term loan facility and long-term debt

Maximum borrowing capacity

$ 200,000,000

330,000,000

500,000,000

Amount outstanding under credit facility

200,000,000

$ 330,000,000

Remaining borrowing capacity

300,000,000

Revolving credit facility | Senior Credit Facility due 2017 | Maximum

Credit facilities, short-term loan facility and long-term debt

Line of Credit Facility, Contingent Increase to Maximum Borrowing Capacity

$ 250,000,000

Revolving credit facility | Senior Credit Facility due 2017 | LIBOR

Credit facilities, short-term loan facility and long-term debt

1.44%

1.41%

1.44%

Term loan | 2013 Term Loan Facility due 2018

1.50%

1.41%

Credit facilities, short-term loan facility and long-term debt

$ 500,000,000

Borrowings under the facility

$ 500,000,000

$ 500,000,000

Term loan | 2013 Term Loan Facility due 2018 | Base rate borrowings | Federal funds rate

Credit facilities, short-term loan facility and long-term debt

Term loan | 2013 Term Loan Facility due 2018 | Base rate borrowings | LIBOR

0.50%

Credit facilities, short-term loan facility and long-term debt

Term loan | 2013 Term Loan Facility due 2018 | Base rate borrowings | Base rate | Minimum

1.00%

Credit facilities, short-term loan facility and long-term debt

Term loan | 2013 Term Loan Facility due 2018 | Base rate borrowings | Base rate | Maximum

0.125%

Credit facilities, short-term loan facility and long-term debt

Term loan | 2013 Term Loan Facility due 2018 | LIBOR borrowings | LIBOR

1.00%

Credit facilities, short-term loan facility and long-term debt

1.44%

1.41%

Term loan | 2013 Term Loan Facility due 2018 | LIBOR borrowings | LIBOR | Minimum

1.50%

1.41%

Credit facilities, short-term loan facility and long-term debt

Term loan | 2013 Term Loan Facility due 2018 | LIBOR borrowings | LIBOR | Maximum

1.125%

Credit facilities, short-term loan facility and long-term debt

Credit facilities, short-term loan facility and long-term debt

2.00%

Term loan | 2015 Term Loan Facility due 2018

1.85%

1.82%

Credit facilities, short-term loan facility and long-term debt

$ 170,000,000

Term loan | 2015 Term Loan Facility due 2018 | LIBOR

$ 170,000,000

Amount borrowed

$ 170,000,000

Credit facilities, short-term loan facility and long-term debt

1.47%

Unsecured debt | 4.65% Senior Notes due 2021

1.39%

Credit facilities, short-term loan facility and long-term debt

4.65%

Discount

$ 0

Unsecured debt | 4.375% Senior Notes due 2025

$ 350,000,000

Credit facilities, short-term loan facility and long-term debt

4.375%

Discount

$ 1,000,000

$ 349,000,000

Unsecured debt | 5.09% Senior Notes due 2015

$ 350,000,000

Net proceeds

$ 346,000,000

Credit facilities, short-term loan facility and long-term debt

5.09%

Unsecured debt | 5.29% Senior Notes due 2020

$ 75,000,000

Credit facilities, short-term loan facility and long-term debt

5.29%

Unsecured debt | 5.69% Senior Notes due 2035

$ 100,000,000

Credit facilities, short-term loan facility and long-term debt

5.69%

Unsecured debt | Term Loan Facility due 2019

$ 150,000,000

Credit facilities, short-term loan facility and long-term debt

Secured debt | 3.82% Series D Senior Notes due 2017

$ 75,000,000

Credit facilities, short-term loan facility and long-term debt

3.82%

$ 16,000,000

$ 20,000,000

Credit facilities, short-term loan facility and long-term debt

Percentage of debt to total capitalization, actual

43.80%

GTN | 5.09% Senior Notes due 2015

Credit facilities, short-term loan facility and long-term debt

GTN | Unsecured debt | Term Loan Facility due 2019 | LIBOR

5.09%

Credit facilities, short-term loan facility and long-term debt

1.16%

1.15%

GTN | Unsecured debt | Senior Notes and Term Loan Facility due 2019 | Maximum

$ 75,000,000

Credit facilities, short-term loan facility and long-term debt

Percentage of debt to total capitalization, covenant

70.00%

[1]	Recast as discussed in Note 2 and Note 6.

DEBT AND CREDIT FACILITIES - Principal Payments Required (Details 2) $ in Millions	Dec. 31, 2015 USD ($)
Principal repayments required on debt
2016	$ 14
2017	222
2018	690
2019	35
2020	100
Thereafter	849
Total debt	$ 1,910

OTHER LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
OTHER LIABILITIES
Regulatory liabilities	$ 24	$ 23
Other liabilities	3	3
Other liabilities, total	$ 27	$ 26

PARTNERS' EQUITY - Ownership (Details) - shares

12 Months Ended

Apr. 01, 2015

May 22, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Common units | Limited Partners

64,300,000

63,600,000

62,300,000

^[1]

Non-affiliates | Common units | Limited Partners

64,317,449

TC PipeLines GP, Inc. | General Partner

47,232,618

IDRs ownership (as a percent)

100.00%

Ownership interest in the Partnership (as a percent)

2.00%

TC PipeLines GP, Inc. | Common units | Limited Partners

TransCanada Corporation and subsidiaries | Common units | Limited Partners

5,797,106

TransCanada | Common units | Limited Partners

17,084,831

Ownership interest in the Partnership (as a percent)

11,287,725

26.60%

TransCanada | Class B units | Limited Partners

Ownership interest in the Partnership (as a percent)

1,900,000

100.00%

[1]	Recast as discussed in Note 2 and Note 6.

PARTNERS' EQUITY - ATM Equity Issuance Program (Details 2) shares in Millions, $ in Millions			1 Months Ended	12 Months Ended
	Apr. 01, 2015 USD ($)	May 22, 2013	Aug. 31, 2014 USD ($) Institution	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013
Partners' Equity
Equity contribution				$ 2.0
General Partner
Partners' Equity
Equity contribution	$ 2.0			$ 2.0
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Ownership interest in the Partnership (as a percent)	2.00%	2.00%		2.00%	2.00%	2.00%
ATM Equity Issuance Program \| Common units
Partners' Equity
Number of financial institutions \| Institution			5
Aggregate offering price of units			$ 200.0
Units sold \| shares				0.7	1.3
Net proceeds from public offering of common units				$ 43.0	$ 71.0
Sales agent commissions				0.4	1.0
ATM Equity Issuance Program \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution				$ 1.0	$ 2.0
ATM Equity Issuance Program \| Minimum \| Common units
Partners' Equity
Number of managers to agree with equity sale method \| Institution			1

PARTNERS' EQUITY - Issuance of Class B Units (Details 3)	Apr. 01, 2015
GTN \| TransCanada \| Distributions \| Class B units
Partners' Equity
Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)	30.00%

PARTNERS' EQUITY - May 2013 Equity Issuance (Details 4) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Apr. 01, 2015	May 22, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Partners' Equity
Equity contribution			$ 2
General Partner
Partners' Equity
Equity contribution	$ 2		$ 2
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Ownership interest in the Partnership (as a percent)	2.00%	2.00%	2.00%	2.00%	2.00%
Equity Issuance, May 2013 \| TC PipeLines GP, Inc. \| General Partner
Partners' Equity
Equity contribution		$ 8
Equity Issuance, May 2013 \| Common units
Partners' Equity
Units sold		8,855,000
Units sold in public offering pursuant to exercise of underwriters' option		1,155,000
Price per common unit in public offering		$ 43.85
Gross proceeds from sale of common units		$ 388
Net proceeds from public offering of common units		$ 373

ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in accumulated other comprehensive loss (AOCL) by components
Balance as of beginning year	$ 1,352
Net other comprehensive loss		$ (1)
Balance as of end year	1,151	1,352
Cash flow hedges
Changes in accumulated other comprehensive loss (AOCL) by components
Balance as of beginning year	(2)	(1)	$ (1)
Other comprehensive loss before reclassifications		(1)
Amounts reclassified from AOCL
Balance as of end year	$ (2)	$ (2)	$ (1)

FINANCIAL CHARGES AND OTHER (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

FINANCIAL CHARGES AND OTHER

Interest expense

$ 58

$ 48

$ 42

Amortization of debt issue costs

^[1]

Net realized loss related to the interest rate swaps and options

Other

(5)

(1)

Financial charges and other

$ 56

$ 50

$ 44

^[1]

[1]	Recast as discussed in Note 2 and Note 6.

NET INCOME (LOSS) PER COMMON UNIT - General Partner Effective Interest and Allocated Incentive Distributions (Details)			12 Months Ended
	Apr. 01, 2015	May 22, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
TC PipeLines GP, Inc. \| General Partner
Partners' Equity
General partner interest (as a percent)	2.00%	2.00%	2.00%	2.00%	2.00%

NET INCOME (LOSS) PER COMMON UNIT - Determination and Terms of Class B Unit Distributions (Details 2) - USD ($)
$ / shares in Units, shares in Millions

3 Months Ended

9 Months Ended

12 Months Ended

Apr. 01, 2015

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Net income (loss) per common unit

Net income attributable to controlling interests

$ (137,000,000)

$ 49,000,000

$ 44,000,000

$ 57,000,000

$ 47,000,000

$ 31,000,000

$ 37,000,000

$ 57,000,000

$ 13,000,000

$ 172,000,000

$ 155,000,000

^[1]

Net income attributed to GTN and Bison's former parent

(26,000,000)

Net income allocable to General and Limited Partners

13,000,000

172,000,000

129,000,000

Incentive distributions attributable to the General Partner

(3,000,000)

(1,000,000)

Net income (loss) allocable to the General Partner and common units

$ (2,000,000)

171,000,000

129,000,000

Net Income (loss) allocable to the General Partner's two percent interest

3,000,000

Priority income allocation for incentive distributions allocated to General Partner (as a percent)

100.00%

Class B units

Net income (loss) per common unit

Net income (loss) attributable to limited partners

$ 12,000,000

Net income (loss) attributable to limited partners

Net income (loss) per common unit

$ (2,000,000)

$ 168,000,000

$ 126,000,000

^[1]

Weighted average common units outstanding - basic (in units)

63.9

62.7

58.9

^[1]

Weighted average common units outstanding - diluted (in units)

63.9

62.7

58.9

Net income per common unit - basic (in dollars per unit)

$ (2.24)

$ 0.70

$ 0.66

$ 0.88

$ 0.71

$ 0.48

$ 0.58

$ 0.90

$ (0.03)

$ 2.67

$ 2.13

^[1]

Net income per common unit - diluted (in dollars per unit)

$ (0.03)

$ 2.67

$ 2.13

GTN | Class B units | TransCanada | Distributions

Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)

30.00%

Percentage applied to GTN's distributable cash flow for the nine months ending December 31, 2015

30.00%

Prorated threshold of GTN's distributions for payment to Class B units

$ 15,000,000

30% of GTN's distributable cash flow

$ 27,000,000

[1]	Recast as discussed in Note 2 and Note 6.

CASH DISTRIBUTIONS - Quarterly Distributions (Details)			12 Months Ended
CASH DISTRIBUTIONS - Quarterly Distributions (Details)	Apr. 01, 2015	May 22, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash distributions
Period after the end of each quarter within which quarterly cash distributions to partners are to be paid			45 days
General Partner \| TC PipeLines GP, Inc.
Cash distributions
General partner interest (as a percent)	2.00%	2.00%	2.00%	2.00%	2.00%

CASH DISTRIBUTIONS - General Partner Distribution Incentives (Details 2) - $ / shares

12 Months Ended

Apr. 01, 2015

May 22, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Schedule of Capitalization, Equity [Line Items]

Limited Partners | Common units

64,300,000

63,600,000

62,300,000

^[1]

Schedule of Capitalization, Equity [Line Items]

Limited Partners | Common units | TC PipeLines GP, Inc.

64,317,449

Schedule of Capitalization, Equity [Line Items]

General Partner | TC PipeLines GP, Inc.

5,797,106

Schedule of Capitalization, Equity [Line Items]

General partner interest (as a percent)

2.00%

Minimum Quarterly Distribution

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.45

Minimum Quarterly Distribution | Limited Partners | Common units

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, Common Unitholders (as a percent)

98.00%

Minimum Quarterly Distribution | General Partner

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, General Partner (includes IDRs)

2.00%

First Target Distribution | Minimum

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.45

First Target Distribution | Maximum

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.81

First Target Distribution | Limited Partners | Common units

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, Common Unitholders (as a percent)

98.00%

First Target Distribution | General Partner

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, General Partner (includes IDRs)

2.00%

Second Target Distribution | Minimum

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.81

Second Target Distribution | Maximum

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.88

Second Target Distribution | Limited Partners | Common units

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, Common Unitholders (as a percent)

85.00%

Second Target Distribution | General Partner

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, General Partner (includes IDRs)

15.00%

Thereafter | Minimum

Schedule of Capitalization, Equity [Line Items]

Total Quarterly Distribution Per Unit Target Amount (in dollars per unit)

$ 0.88

Thereafter | Limited Partners | Common units

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, Common Unitholders (as a percent)

75.00%

Thereafter | General Partner

Schedule of Capitalization, Equity [Line Items]

Marginal Percentage Interest in Distribution, General Partner (includes IDRs)

25.00%

[1]	Recast as discussed in Note 2 and Note 6.

CASH DISTRIBUTIONS - Distributions by Payment Date (Details 3) - USD ($)

9 Months Ended

12 Months Ended

Feb. 12, 2016

Jan. 21, 2016

Nov. 13, 2015

Oct. 22, 2015

Aug. 14, 2015

Jul. 23, 2015

May 15, 2015

Apr. 23, 2015

Apr. 01, 2015

Feb. 13, 2015

Jan. 22, 2015

Nov. 14, 2014

Oct. 23, 2014

Aug. 14, 2014

Jul. 23, 2014

May 15, 2014

Apr. 25, 2014

Feb. 14, 2014

Jan. 16, 2014

Nov. 14, 2013

Oct. 24, 2013

Aug. 14, 2013

Jul. 23, 2013

May 15, 2013

Apr. 23, 2013

Feb. 14, 2013

Jan. 17, 2013

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

General Partner 2% paid

$ 1,000,000

$ 2,000,000

$ 1,000,000

1,000,000

$ 2,000,000

$ 1,000,000

$ 0

Total Cash Distribution

$ 59,000,000

$ 55,000,000

$ 54,000,000

$ 52,000,000

$ 51,000,000

$ 43,000,000

$ 228,000,000

$ 212,000,000

$ 188,000,000

^[1]

Per Unit Distribution, declared (in dollars per unit)

$ 0.89

$ 0.84

$ 0.81

$ 0.78

Per Unit Distribution, paid (in dollars per unit)

$ 0.89

$ 0.84

$ 0.81

$ 0.78

Limited Partners, Distribution declared

$ 57,000,000

$ 56,000,000

$ 54,000,000

$ 53,000,000

$ 51,000,000

$ 50,000,000

$ 42,000,000

GTN | Class B units | TransCanada | Distributions

$ 57,000,000

$ 56,000,000

$ 54,000,000

$ 53,000,000

$ 51,000,000

$ 50,000,000

$ 42,000,000

Portion of GTN's annual distributions to which the Class B units are entitled to receive a percentage share of the distributions above threshold (as a percent)

30.00%

Percentage applied to GTN's distributable cash flow for the nine month ended December 31, 2015

30.00%

Prorated threshold of GTN's distributions for payment to Class B units

$ 15,000,000

Subsequent event

General Partner 2% paid

$ 1,000,000

Subsequent event | Common units

1,000,000

Total Cash Distribution

$ 71,000,000

Per Unit Distribution, declared (in dollars per unit)

$ 0.89

Per Unit Distribution, paid (in dollars per unit)

$ 0.89

Limited Partners, Distribution declared

$ 57,000,000

Subsequent event | Class B units

$ 57,000,000

Limited Partners, Distribution declared

$ 12,000,000

Change in accounts receivable and other

$ 12,000,000

[1]	Recast as discussed in Note 2 and Note 6.

CHANGE IN OPERATING WORKING CAPITAL - Components (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

CHANGE IN OPERATING WORKING CAPITAL

$ 2

$ 1

Change in accounts payable and accrued liabilities

$ (3)

(9)

Change in accounts payable to affiliates

(10)

(2)

Change in accrued interest

Change in operating working capital

$ (9)

$ 17

$ (8)

^[1]

[1]	Recast as discussed in Note 2 and Note 6.

CHANGE IN OPERATING WORKING CAPITAL - Certain Non-Cash Items Excluded from Change in Operating Working Capital (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013	Jan. 01, 2016
Non-cash items
Accruals for capital expenditures	$ 10
Accruals for costs related to acquisition	2
GTN
Non-cash items
Accruals for capital expenditures		$ 10
Portland Natural Gas Transmission System \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Non-cash items
Accruals for costs related to acquisition	$ 2
Subsequent event \| Portland Natural Gas Transmission System \| Former parent, TransCanada subsidiaries \| Transaction between entities under common control
Non-cash items
Interest acquired (as a percent)			49.90%

TRANSACTIONS WITH MAJOR CUSTOMERS (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Trade accounts receivable

Revenues

$ 89

$ 83

$ 85

$ 87

$ 80

$ 82

$ 87

$ 344

$ 336

$ 341

^[1]

Total revenues | Customer concentration risk | Anadarko Energy Services Company

Total revenues | Customer concentration risk | Pacific Gas and Electric Company

Revenues

Accounts receivable and other | Amounts owed by major customers | Anadarko Energy Services Company

Revenues

$ 46

Trade accounts receivable

Accounts receivable and other | Amounts owed by major customers | Pacific Gas and Electric Company

Trade accounts receivable

$ 3

$ 4

$ 3

$ 4

[1]	Recast as discussed in Note 2 and Note 6.

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ in Millions		3 Months Ended			4 Months Ended	12 Months Ended
	Apr. 11, 2013	Dec. 31, 2015	Mar. 31, 2015	Jun. 30, 2013	May 03, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 01, 2015	Oct. 01, 2014	Jul. 01, 2013
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates		$ 5				$ 5	$ 15
Amount included in receivables from related party							1
Bison
Capital and operating costs charged to the pipeline systems and amount payable
Total cash call issued to fund debt repayment				$ 24
Bison \| TransCanada
Capital and operating costs charged to the pipeline systems and amount payable
Equity contribution form former parent				$ 18
Great Lakes
Capital and operating costs charged to the pipeline systems and amount payable
Total cash call issued to fund debt repayment		$ 10	$ 9
Great Lakes \| TransCanada
Capital and operating costs charged to the pipeline systems and amount payable
Ownership interest (as a percent)		53.55%				53.55%
Bison \| TransCanada
Capital and operating costs charged to the pipeline systems and amount payable
Ownership interest (as a percent)				75.00%
General Partner \| Reimbursement of costs of services provided
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						$ 3	3	$ 3
TransCanada's subsidiaries \| GTN
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates		$ 3				3	10
TransCanada's subsidiaries \| GTN \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						30	30	28
Impact on the Partnership's net income attributable to controlling interests						$ 25	$ 19	$ 19
Percentage of capital and operating costs charged						100.00%	100.00%	100.00%
TransCanada's subsidiaries \| Northern Border
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates		5				$ 5	$ 10
TransCanada's subsidiaries \| Northern Border \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						$ 36	$ 35	$ 30
Percentage of capital and operating costs charged						100.00%	100.00%	100.00%
TransCanada's subsidiaries \| Bison
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates							$ 2
TransCanada's subsidiaries \| Bison \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						$ 4	6	$ 5
Impact on the Partnership's net income attributable to controlling interests						$ 4	$ 4	$ 4
Percentage of capital and operating costs charged						100.00%	100.00%	100.00%
TransCanada's subsidiaries \| Great Lakes
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates		3				$ 3	$ 9
Amount included in receivables from related party		17				17	15
TransCanada's subsidiaries \| Great Lakes \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						$ 30	$ 30	$ 31
Percentage of capital and operating costs charged						100.00%	100.00%	100.00%
TransCanada's subsidiaries \| Great Lakes \| Transportation contracts
Capital and operating costs charged to the pipeline systems and amount payable
Revenues from related party						$ 125	$ 71	$ 68
TransCanada's subsidiaries \| Great Lakes \| Transportation contracts \| Total revenues \| Customer concentration risk
Capital and operating costs charged to the pipeline systems and amount payable
Percent of total revenues						71.00%	49.00%	55.00%
TransCanada's subsidiaries \| Great Lakes \| Affiliated rental revenue
Capital and operating costs charged to the pipeline systems and amount payable
Revenues from related party						$ 2	$ 2	$ 1
TransCanada's subsidiaries \| North Baja Pipeline, LLC
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates							1
TransCanada's subsidiaries \| North Baja Pipeline, LLC \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						5	5	4
Impact on the Partnership's net income attributable to controlling interests						5	4	4
TransCanada's subsidiaries \| Tuscarora Gas Transmission Company
Capital and operating costs charged to the pipeline systems and amount payable
Accounts payable to affiliates		1				1	1
TransCanada's subsidiaries \| Tuscarora Gas Transmission Company \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Costs charged						4	4	4
Impact on the Partnership's net income attributable to controlling interests						4	4	4
TransCanada's subsidiaries \| Northern Border \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Impact on the Partnership's net income attributable to controlling interests						14	16	14
TransCanada's subsidiaries \| Great Lakes
Capital and operating costs charged to the pipeline systems and amount payable
Revenue from TransCanada and its affiliates included in the Partnership's equity earnings						59	34	32
TransCanada's subsidiaries \| Great Lakes \| Capital and operating costs
Capital and operating costs charged to the pipeline systems and amount payable
Impact on the Partnership's net income attributable to controlling interests						$ 13	13	$ 14
Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| GTN
Capital and operating costs charged to the pipeline systems and amount payable
Interest acquired (as a percent)									30.00%		45.00%
Additional acquisition consideration relating to Carty Lateral project	$ 25
Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| Bison
Capital and operating costs charged to the pipeline systems and amount payable
Interest acquired (as a percent)										30.00%	45.00%
ANR Pipeline Company \| Great Lakes \| Firm service between Michigan and Wisconsin
Capital and operating costs charged to the pipeline systems and amount payable
Deferred revenue related to services performed					$ 14		$ 9
Deferred revenue recognized		$ 23

QUARTERLY FINANCIAL DATA (unaudited) (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Impairment of equity-method investment

$ 89

$ 83

$ 85

$ 87

$ 80

$ 82

$ 87

$ 344

$ 336

$ 341

^[1]

Equity earnings

^[1]

(199)

Net income (loss) attributable to controlling interests

(137)

204

191

^[1]

(137)

172

155

^[1]

Cash distributions paid

$ 59

$ 55

$ 54

$ 52

$ 51

Great Lakes | Nonrecurring fair value measurement

Equity earnings

Impairment of equity-method investment

$ (199)

Northern Border | Nonrecurring fair value measurement

Equity earnings

$ 66

$ 69

$ 64

Impairment of equity-method investment

$ 0

Net income per common unit (in dollars per unit)

$ (2.24)

$ 0.70

$ 0.66

$ 0.88

$ 0.71

$ 0.48

$ 0.58

$ 0.90

$ (0.03)

$ 2.67

$ 2.13

^[1]

[1]	Recast as discussed in Note 2 and Note 6.

FAIR VALUE MEASUREMENTS - Estimated Fair Value of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2015	Mar. 13, 2015	Dec. 31, 2014
Unsecured debt \| 4.65% Senior Notes due 2021
Financial Instruments
Stated interest rate (as a percent)	4.65%		4.65%
Unsecured debt \| 4.375% Senior Notes due 2025
Financial Instruments
Stated interest rate (as a percent)	4.375%	4.375%
Unsecured debt \| 5.09% Senior Notes due 2015
Financial Instruments
Stated interest rate (as a percent)			5.09%
Unsecured debt \| 5.29% Senior Notes due 2020
Financial Instruments
Stated interest rate (as a percent)	5.29%		5.29%
Unsecured debt \| 5.69% Senior Notes due 2035
Financial Instruments
Stated interest rate (as a percent)	5.69%		5.69%
Secured debt \| 3.82% Series D Senior Notes due 2017
Financial Instruments
Stated interest rate (as a percent)	3.82%		3.82%
Carrying Value
Financial Instruments
Debt	$ 1,910		$ 1,695
Carrying Value \| Term loan \| Short-Term Loan Facility due 2015
Financial Instruments
Debt			170
Carrying Value \| Revolving credit facility \| Senior Credit Facility due 2017
Financial Instruments
Debt	200		330
Carrying Value \| Term loan \| 2013 Term Loan Facility due 2018
Financial Instruments
Debt	500		500
Carrying Value \| Term loan \| 2015 Term Loan Facility due 2018
Financial Instruments
Debt	170
Carrying Value \| Unsecured debt \| 4.65% Senior Notes due 2021
Financial Instruments
Debt	350		350
Carrying Value \| Unsecured debt \| 4.375% Senior Notes due 2025
Financial Instruments
Debt	349
Carrying Value \| Unsecured debt \| 5.09% Senior Notes due 2015
Financial Instruments
Debt			75
Carrying Value \| Unsecured debt \| 5.29% Senior Notes due 2020
Financial Instruments
Debt	100		100
Carrying Value \| Unsecured debt \| 5.69% Senior Notes due 2035
Financial Instruments
Debt	150		150
Carrying Value \| Unsecured debt \| Term Loan Facility due 2019
Financial Instruments
Debt	75
Carrying Value \| Secured debt \| 3.82% Series D Senior Notes due 2017
Financial Instruments
Debt	16		20
Fair Value \| Level 2
Financial Instruments
Debt	1,873		1,751
Fair Value \| Level 2 \| Term loan \| Short-Term Loan Facility due 2015
Financial Instruments
Debt			170
Fair Value \| Level 2 \| Revolving credit facility \| Senior Credit Facility due 2017
Financial Instruments
Debt	200		330
Fair Value \| Level 2 \| Term loan \| 2013 Term Loan Facility due 2018
Financial Instruments
Debt	500		500
Fair Value \| Level 2 \| Term loan \| 2015 Term Loan Facility due 2018
Financial Instruments
Debt	170
Fair Value \| Level 2 \| Unsecured debt \| 4.65% Senior Notes due 2021
Financial Instruments
Debt	338		375
Fair Value \| Level 2 \| Unsecured debt \| 4.375% Senior Notes due 2025
Financial Instruments
Debt	314
Fair Value \| Level 2 \| Unsecured debt \| 5.09% Senior Notes due 2015
Financial Instruments
Debt			76
Fair Value \| Level 2 \| Unsecured debt \| 5.29% Senior Notes due 2020
Financial Instruments
Debt	108		111
Fair Value \| Level 2 \| Unsecured debt \| 5.69% Senior Notes due 2035
Financial Instruments
Debt	151		168
Fair Value \| Level 2 \| Unsecured debt \| Term Loan Facility due 2019
Financial Instruments
Debt	75
Fair Value \| Level 2 \| Secured debt \| 3.82% Series D Senior Notes due 2017
Financial Instruments
Debt	$ 17		$ 21

FAIR VALUE MEASUREMENTS - Interest Rate Swaps (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 01, 2013
Accounts receivable
Interest rate derivatives
Maximum counterparty credit exposure	$ 35,000,000	$ 35,000,000
Term loan \| 2013 Term Loan Facility due 2018
Interest rate derivatives
Amount of facility	500,000,000			$ 500,000,000
Interest rate swaps \| Term loan \| 2013 Term Loan Facility due 2018
Interest rate derivatives
Amount of variable-rate debt hedged	$ 150,000,000
Weighted average fixed interest rate (as a percent)	2.79%
Hedges of cash flows \| Interest rate swaps
Interest rate derivatives
Change in fair value of interest rate derivative instruments recognized in other comprehensive income	$ 0	1,000,000
Hedges of cash flows \| Interest rate swaps \| Maximum
Interest rate derivatives
Change in fair value of interest rate derivative instruments recognized in other comprehensive income			$ 1,000,000
Hedges of cash flows \| Interest rate swaps \| Financial charges and other
Interest rate derivatives
Net realized loss related to the interest rate swaps	2,000,000	2,000,000	1,000,000
Designated as hedge \| Interest rate swaps \| Recurring fair value measurement \| Level 2
Interest rate derivatives
Fair value of derivatives, gross	1,000,000	1,000,000
Fair value of derivatives, net	$ 1,000,000	$ 1,000,000
Designated as hedge \| Interest rate swaps \| Recurring fair value measurement \| Level 2 \| Maximum
Interest rate derivatives
Fair value of derivatives, gross			1,000,000
Fair value of derivatives, net			$ 1,000,000

FAIR VALUE MEASUREMENTS - Impairment of Equity-Method Investment (Details 3) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015
Fair value measurements
Impairment charge recognized on equity method investment	$ 199	$ 199
Nonrecurring fair value measurement \| Great Lakes
Fair value measurements
Impairment charge recognized on equity method investment	$ 199

ACCOUNTS RECEIVABLE AND OTHER (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
ACCOUNTS RECEIVABLE AND OTHER
Trade accounts receivable, net of allowance of nil	$ 31	$ 30
Accounts receivable from affiliates		1
Other	4	4
Accounts receivable and other	35	35
Trade accounts receivable, allowance	$ 0	$ 0

CONTINGENCIES (Details) $ in Millions	Apr. 01, 2015 USD ($)
Former parent, TransCanada subsidiaries \| Transaction between entities under common control \| GTN \| Partnership interest \| Class B units
Contingencies
Equity issuance	$ 95

SUBSEQUENT EVENTS - Distributions (Details) - USD ($)

3 Months Ended

9 Months Ended

12 Months Ended

Feb. 12, 2016

Feb. 01, 2016

Jan. 21, 2016

Jan. 11, 2016

Nov. 13, 2015

Oct. 22, 2015

Aug. 14, 2015

Jul. 23, 2015

May 15, 2015

Apr. 23, 2015

Apr. 01, 2015

Feb. 13, 2015

Jan. 22, 2015

Nov. 14, 2014

Oct. 23, 2014

Aug. 14, 2014

Jul. 23, 2014

May 15, 2014

Apr. 25, 2014

Feb. 14, 2014

Jan. 16, 2014

Nov. 14, 2013

Oct. 24, 2013

Aug. 14, 2013

Jul. 23, 2013

May 22, 2013

May 15, 2013

Apr. 23, 2013

Feb. 14, 2013

Jan. 17, 2013

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Feb. 28, 2007

Total cash distribution

$ 59,000,000

$ 55,000,000

$ 54,000,000

$ 52,000,000

$ 51,000,000

$ 1,000,000

$ 2,000,000

$ 1,000,000

$ 0

50.00%

46.45%

Per Unit Distribution, declared (in dollars per unit)

$ 0.89

$ 0.84

$ 0.81

$ 0.78

Distributions declared

$ 57,000,000

$ 56,000,000

$ 54,000,000

$ 53,000,000

$ 51,000,000

$ 50,000,000

$ 42,000,000

$ 57,000,000

$ 56,000,000

$ 54,000,000

$ 53,000,000

$ 51,000,000

$ 50,000,000

$ 42,000,000

Class B units | GTN | Distributions | TransCanada

64,300,000

63,600,000

64,300,000

63,600,000

62,300,000

^[1]

Percentage applied to GTN's distributable cash flow for the nine months ending December 31, 2015

30.00%

Prorated threshold of GTN's distributions for payment to Class B units

$ 15,000,000

Limited Partners | Common units

Limited Partners | Common units | TC PipeLines GP, Inc.

64,317,449

Limited Partners | Common units | TransCanada

5,797,106

Limited Partners | Class B units | TransCanada

11,287,725

General Partner | TC PipeLines GP, Inc.

1,900,000

Ownership interest in the Partnership (as a percent)

2.00%

Subsequent event

Total cash distribution

$ 59,000,000

Subsequent event | Distribution declared | Northern Border

1,000,000

Subsequent event | Distribution declared | Great Lakes

Partnership distribution

$ 44,000,000

Subsequent event | Cash Distribution Paid | Northern Border

Partnership distribution

$ 42,000,000

Partnership's share of distributions

$ 22,000,000

Subsequent event | Cash Distribution Paid | Great Lakes

Partnership's share of distributions

$ 20,000,000

Subsequent event | TC PipeLines GP, Inc.

General partner cash distributions

2,000,000

Subsequent event | Common units

1,000,000

Per Unit Distribution, declared (in dollars per unit)

$ 0.89

Distributions declared

$ 57,000,000

Subsequent event | Common units | TC PipeLines GP, Inc.

57,000,000

Subsequent event | Common units | TransCanada

5,000,000

Subsequent event | Class B units

10,000,000

Distributions declared

$ 12,000,000