Company: TSLTF
Filing Date: 2025-02-20
Form Type: 40-F
Source: 0001144800-25-000006
Chunk: 0

Company: TRANSALTA CORP
Filing Date: 2025-02-20
Form: 40-F
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### FORM 40-F
[Check one]

☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934

<div align='center'>OR</div>

☒ ANNUAL REPORT PURSUANT TO SECTION 13(a) OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

| For the fiscal year ended |     | Dec. 31, 2024 |     | Commission file number |     | 001-15214 |

### TRANSALTA CORPORATION
<div align='center'>(Exact name of Registrant as specified in its charter)</div>

#### Not applicable
<div align='center'>(Translation of Registrant’s name into English (if applicable))</div>

#### Canada
<div align='center'>(Province or other jurisdiction of incorporation or organization)</div>

#### 4911
<div align='center'>(Primary Standard Industrial Classification Code Number (if applicable))</div>

#### Not Applicable
<div align='center'>(I.R.S Employer Identification Number (if applicable))</div>

#### 1400, 1100 - 1st Street S.E.,

#### Calgary, Alberta, Canada, T2G 1B1,
<div align='center'>( 403) 267-7110

(Address and telephone number of Registrant’s principal executive offices)</div>

#### TransAlta Centralia Generation LLC
<div align='center'>913 Big Hanaford Road, Centralia, Washington 98531, ( 360) 736-9901

(Name, address (including zip code) and telephone number (including area code)

of agent for service in the United States)</div>

Securities registered or to be registered pursuant to Section 12(b) of the Act:

| Title of each class          |     | Trading Symbols |     | Name of each exchange   |
|                              |     |                 |     | on which registered     |
| Common Shares, no par value  |     | TAC             |     | New York Stock Exchange |
| Common Share Purchase Rights |     | TAC             |     | New York Stock Exchange |

Securities registered or to be registered pursuant to Section 12(g) of the Act:

#### None
Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act