Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 389

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 389
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| • |     | Impairment, net of reversals, related to certain Wind and Solar facilities due to changes in 
 expected production volumes and lower power price assumptions in the third quarter of 2025.  |

(Loss) earnings before income taxes has been impacted by the following:

| • |     | The items described above; |

| • |     | Fair value change in contingent consideration payable during 2025 driven by updated expected sale 
 proceeds related to the Required Divestitures; and                                                |

| • |     | Higher interest expense due to higher interest on debt driven by the addition of Heartland term                                                                                                                                    
 facility, lower capitalized interest during 2025 as a result of lower capital activity during the nine months ended Sept. 30, 2025, and higher accretion of provisions in the current period compared to the same periods in 2024. |

Net (loss) earnings attributable to common shareholders has been impacted by fluctuations in current and deferred tax expense with (loss) earnings before tax across the quarters. Cash flow from operating activities has been impacted by the following:

| • |     | The items described above; |

| • |     | Favourable changes in non-cash operating working capital                                                                                                                                                                                            
 balances in the third and second quarters of 2025, compared to same periods in prior year, due to timing of cash receipts, partially offset by higher payables and accrued liabilities, and lower prepaid expense due to insurance driven timing of 
 payments; and                                                                                                                                                                                                                                       |

| • |     | Lower provisions and other non-cash items in the second and 
 first quarter of 2025 compared to the same periods in 2024. |

| M42 |     | TransAlta Corporation |

Management’s Discussion and Analysis Financial Position The following table highlights significant changes in the Condensed Consolidated Statements of Financial Position from Dec. 31, 2024 to Sept. 30, 2025:

|                                                         |     | Sept. 30, 2025 |       |     | Dec. 31, 2024 |       |     | Increase/(decrease) |      |   |
|:--------------------------------------------------------|:----|:---------------|------:|:----|:--------------|------:|:----|:--------------------|-----:|:--|
| Assets                                                  |     |                |       |     |               |       |     |                     |      |   |
| Current assets                                          |     |                |       |     |