Did you get a W-2 for 2023? If so, you have to file it on a 2023 tax return, even if you didn't get the money until 2024.
If you did not get a W-2 for 2023 you have nothing to file for 2023. The pay that you received in January 2024 should be included in the 2024 W-2 that you get in January 2025. You will include it in your 2024 tax return.
