Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 376

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 376
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 for the three months ended Sept. 30, 2025 increased compared to the same period in 2024, primarily due to:

| • |     | Higher environmental and tax attributes revenue driven by an increase in sales of emission credits 
 to third parties; and                                                                              |

| • |     | Favourable pricing for Oklahoma facilities; partially offset by |

| • |     | Lower wind resource across Canada and United States. |

Adjusted EBITDA for the three months ended Sept. 30, 2025 was comparable to the same period in 2024 primarily due to:

| • |     | Higher adjusted revenue; partially offset by |

| • |     | Lower net other operating income due to no liquidated damages recognized in the current period. |

Adjusted loss before income taxes for the three months ended Sept. 30, 2025 was comparable to the same period in 2024. Loss before income taxes for the three months ended Sept. 30, 2025 increased compared to in the same period in 2024 due to an impairment charge, net of impairment reversals on certain facilities driven by changes in expected production volumes and price assumptions. Adjusted revenues for the nine months ended Sept. 30, 2025 increased compared to the same period in 2024, primarily due to:

| • |     | The impact from the White Rock and Horizon Hill wind facilities which achieved commercial operation 
 in the first half of 2024;                                                                          |

| • |     | Higher environmental and tax attributes revenues due to the increased sales of emission credits to 
 third parties and intercompany sales to the Gas segment; and                                       |

| • |     | Higher production volumes in Eastern Canada due to higher wind resource; partially offset by |

| • |     | Lower Alberta spot power prices; and |

| • |     | Lower production volumes in Alberta due to lower wind resource. |

Adjusted EBITDA for the nine months ended Sept. 30, 2025 increased compared to the same period in 2024, primarily due to:

| • |     | Higher adjusted revenues as explained by the factors above; partially offset by |

| • |     | Higher OM&A mainly due to the addition of new wind facilities in the first half of 2024. |

Adjusted earnings before income taxes for the the nine months ended Sept. 30, 2025 were comparable to the same period in 2024, primarily due to:

| • |     | Higher adjusted EBITDA as explained above;