Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 403

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 403
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 |     |       |    (5 | ) |     |                |   — |   |     |             |   — |   |     |            |    (5 | ) |
| Earnings (loss) before income                    
 taxes                                            |     |       | 239 |   |     |          |    7 |   |     |     |   318 |   |     |            |  31 |   |     |           | 123 |   |     |           | (348 | ) |     |       |   370 |   |     |                |   — |   |     |             |   — |   |     |            |   370 |   |

| (1) | The Skookumchuck wind facility has been included on a proportionate basis in the Wind and Solar 
 segment.                                                                                        |

| (2) | Adjusted EBITDA, adjusted earnings (loss) before income taxes are non-IFRS measures, are not defined, have no standardized meaning under IFRS and may not be comparable to similar measures presented by other issuers. Refer to the Non-IFRS and 
 Supplementary Financial Measures section of this MD&A.                                                                                                                                                                                            |

| (3) | During the first quarter of 2025, our Adjusted EBITDA composition was amended to exclude the                                                                                        
 impact of realized gain (loss) on closed exchange positions and Australian interest income. Therefore, the Company has applied this composition to all previously reported periods. |

| (4) | Realized and unrealized foreign exchange (loss) gain are supplementary financial measures.        
 Refer to the Non-IFRS and Supplementary Financial Measures section of this MD&A for more details. |

| M62 |     | TransAlta Corporation |

Management’s Discussion and Analysis Reconciliation of (Loss) Earnings Before Income Taxes to Adjusted Net (Loss) Earnings attributable to common shareholders The following table reflects reconciliation of (loss) earnings before income taxes to adjusted net (loss) earnings attributable to common shareholders for the three and nine months ended Sept. 30, 2025 and Sept. 30, 2024:

|                                                                 |     | 3 months ended Sept. 30 |       |   |     |      |       |   |     | 9 months ended Sept. 30 |       |   |     |      |       |   |
| (in millions of Canadian dollars except where noted)            |     |                    2025 |       |