Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 114

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 114
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   — |     |      | 359 |     |           |     — |     |      | 285 |     |           |     — |     |      | 258 |
| Total                                   |     |           | 939 |     |      | 655 |     |           | 1,060 |     |      | 539 |     |           | 1,263 |     |      | 521 |

| (1) | Included in OM&A costs for 2023 was $14 million related to the write-down of parts and 
 material inventory related to our natural-gas-fired facilities.                        |

Brazeau — Spinning Reserve Self-Report In 2022 a provision of $20 million was initially recognized in revenue reflecting a potential disgorgement of revenue and $2 million for potential penalties and fines. The final assessment contained no disgorgement of revenue and penalties of $33 million. This resulted in a reversal of the original disgorgement provision in revenue in the year ended Dec. 31, 2024 and recognition of the full amount of the penalties assessed in OM&A. Refer to Note 37 for details. Acquisition-related transaction and restructuring costs During the year ended Dec. 31, 2024, the Company recognized $24 million in acquisition-related transaction and restructuring costs in OM&A costs as part of other operating expenses related to the acquisition of Heartland, mainly comprising severance, legal and consulting fees.

| TransAlta Corporation |     | 2024 Integrated Report |     | F36 |

Notes to the Consolidated Financial Statements 7. Asset Impairment Charges (Reversals) As part of the Company’s monitoring controls, long-range forecasts are prepared for each CGU. The long-range forecast estimates are used to assess the significance of potential indicators of impairment and provide criteria to evaluate adverse changes in operations. The Company also considers the relationship between its market capitalization and its book value, among other factors, when reviewing for indicators of impairment. When indicators of impairment are present, the Company estimates a recoverable amount (the higher of value in use or fair value less costs of disposal) for the affected CGUs using discounted cash flow projections. The valuations are subject to measurement uncertainty from assumptions and inputs to the discount rates, power price forecasts, useful lives of the assets (extending to the last planned asset retirement in 2072) and long-range forecasts, which include changes to production, fuel costs, operating costs and capital expenditures. The Company recognized the