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Accumulated Other Comprehensive Loss (Details) - CAD ($) $ in Millions |  | 12 Months Ended
--- | --- | ---
Oct. 05, 2023 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  |  | $ (164) |  |
Currency translation adjustment |  |  |  |  |
Gains (losses) on translating net assets of foreign operations, net of reclassifications to net earnings, net of tax |  |  | (2) | $ (3) |
Gains (losses) on financial instruments designated as hedges of foreign operations, net of reclassifications to net earnings, net of tax | [1] |  | (28) | 9 | $ (25)
Cash flow hedges |  |  |  |  |
Gains (losses) on derivatives designated as cash flow hedges, net of reclassifications to net earnings and to non-financial assets, net of tax | [2] |  | 213 | 41 | (556)
Other |  |  |  |  |
Intercompany and third-party investments at FVTOCI |  |  |  | 0 |
Accumulated other comprehensive income, end of the period |  |  | 41 | (164) |
Net income tax expense (recovery) relating to gains (losses) on financial instruments |  |  | (4) | 1 | 3
Net impact related to cash flow hedges |  |  | 53 | 27 | (112)
Net of income tax expense |  |  | 3 | (1) | 12
Currency translation adjustment |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  |  | (36) | (39) |
Currency translation adjustment |  |  |  |  |
Gains (losses) on translating net assets of foreign operations, net of reclassifications to net earnings, net of tax |  |  | 30 | (6) |
Gains (losses) on financial instruments designated as hedges of foreign operations, net of reclassifications to net earnings, net of tax |  |  | (28) | 9 |
Other |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | (34) | (36) | (39)
Cash flow hedges |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  |  | (129) | (228) |
Cash flow hedges |  |  |  |  |
Gains (losses) on derivatives designated as cash flow hedges, net of reclassifications to net earnings and to non-financial assets, net of tax |  |  | 194 | 99 |
Other |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | 65 | (129) | (228)
Net impact related to cash flow hedges |  |  | 53 | 27 |
Employee future benefits |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  |  | 3 | 8 |
Employee future benefits |  |  |  |  |
Net actuarial gains on defined benefit plans, net of tax |  |  | 9 | (5) |
Other |  |  |  |  |
Accumulated other comprehensive income, end of the period |  |  | 12 | 3 | 8
Net of income tax expense |  |  | (3) | 1 |
Other |  |  |  |  |
Components and changes in accumulated other comprehensive Income (loss) |  |  |  |  |
Accumulated other comprehensive income, beginning of the period |  |  | (2) | 37 |
Other |  |  |  |  |
Change in ownership of TransAlta Renewables |  | $ 64 | 0 | (64) |
Intercompany and third-party investments at FVTOCI |  |  | 0 | 25 |
Accumulated other comprehensive income, end of the period |  |  | $ (2) | $ (2) | $ 37
[1] | Net of income tax recovery of $4 million for the year ended Dec. 31, 2024 (2023 — $1 million expense, 2022 — $3 million recovery).
[2] | Net of income tax expense of $57 million for the year ended Dec. 31, 2024 (2023 — $10 million expense, 2022 — $138 million recovery).

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- Definition The amount of accumulated items of income and expense (including reclassification adjustments) that are not recognised in profit or loss as required or permitted by other IFRSs. [Refer: IFRSs [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2024-01-01 -Paragraph 55 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_55&doctype=Standard -URIDate 2024-03-27 + Details
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