Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 105

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 105
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 that efforts will result in future value to the Company when determining the amount to be capitalized. Information regarding project development costs is disclosed in Note 23 and information on the write-offof project development costs is disclosed in Note 7. VII. Provisions for Decommissioning and Restoration Activities TransAlta recognizes provisions for decommissioning and restoration obligations as outlined in Note 2(K). Initial decommissioning provisions and subsequent changes thereto are determined using the Company’s best estimate of the required cash expenditures, adjusted to reflect the risks and uncertainties inherent in the timing and amount of settlement. The estimated cash expenditures are present valued using a current, risk-adjusted, market-

| TransAlta Corporation |     | 2024 Integrated Report |     | F26 |

Notes to the Consolidated Financial Statements

based, pre-taxdiscount rate. A change in estimated cash flows, market interest rates or timing could have a material impact on the carrying amount of the provision. Information regarding significant judgments and estimates made during 2022 to 2024 in respect of decommissioning and restoration provisions is disclosed in Notes 7, 19 and 24. VIII. Useful Life of PP&E Each significant component of an item of PP&E is depreciated over its estimated useful life. Estimated useful lives are determined based on current facts and past experience and take into consideration the anticipated physical life of the asset, existing long-term sales agreements and contracts, current and forecasted demand, the potential for technological obsolescence and regulations. The useful lives of PP&E are reviewed at least annually to ensure they continue to be appropriate. Information on changes in useful lives of facilities is disclosed in Note 19. IX. Employee Future Benefits The Company provides pension and other post-employment benefits, such as health and dental benefits, to employees. The cost of providing these benefits is dependent upon many factors, including actual plan experience and estimates and assumptions about future experience. The liability for pension and post-employment benefits and associated costs included in annual compensation expenses are impacted by estimates related to:

| ● |     | Employee demographics, including age, compensation levels, employment periods, the level of 
 contributions made to the plans and earnings on plan assets;                                |

| ● |     | The effects of changes to the provisions of the plans; and |

| ● |     | Changes in key actuarial assumptions, including rates of compensation and health-care cost 
 increases and discount rates.                                                              |

Due to the complexity of the valuation of pension and post-employment benefits, a change in the estimate