Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 369

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 369
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| • |     | The addition of carbon compliance costs from the addition of the Heartland facilities acquired in 
 the fourth quarter of 2024; and                                                                   |

| • |     | An increase in the carbon price from $80 per tonne in 2024 to $95 per tonne in 2025. |

OM&A expensesfor the three months ended Sept. 30, 2025 increased by $36 million, or 25 per cent, compared to the same period in 2024, primarily due to:

| • |     | Full quarter impact from the addition of the Heartland facilities in the fourth quarter of 2024 and 
 associated corporate costs; and                                                                     |

| • |     | Higher spending related to the implementation of an upgrade to our enterprise resource planning 
 (ERP) system.                                                                                   |

Asset impairment chargesfor the the three months ended Sept. 30, 2025 increased by $7 million, or 35 per cent, compared to the same period in 2024, primarily due to:

| • |     | An impairment charge, net of impairment reversals related to the Wind and Solar facilities driven 
 by changes in expected production volumes and price assumptions; partially offset by              |

| • |     | Lower decommissioning and restoration provisions on retired assets driven by lower discount rates 
 compared to the same period in 2024.                                                              |

Foreign exchange gainsfor the three months ended Sept. 30, 2025 increased by $9 million compared to foreign exchange losses in the same period in 2024, primarily due to:

| • |     | Higher unrealized foreign exchange gains due to favourable changes in foreign currency rates; 
 partially offset by                                                                           |

| • |     | Higher realized foreign exchange losses due to hedges settled during the period at unfavourable 
 foreign currency rates.                                                                         |

Loss before income taxesfor the three months ended Sept. 30, 2025 increased by $62 million from earnings before income taxes in the same period in 2024, due to the above noted items. Refer to the Segment Financial Performance and Operating Results section for additional information. Income tax expensefor the three months ended Sept. 30, 2025 decreased by $30 million, or 97 per cent, compared to the same period in 2024, due to the increase in loss before income taxes. Net loss attributable to non-controllinginterestsfor the three months ended Sept. 30, 2025 increased by $6 million compared to