To clarify, you receive a 2024 Form 1099-R for the RMD for 2023 and 2024?
If you received a 2024 Form 1099-R for the RMD for 2023 and 2024, you will enter the Form 1099-R on your 2024 tax return.
You should have filed Form 5329 with your 2023 tax return since you took a late RMD for 2023.
Download 2023 Form 5329 from the IRS website and fill as described in the 5329 instructions page 9, line 54. Print and mail Form 5329 and attach an explanation. Be sure to include your address on page 1 of the form and your signature and the date on page 2 of the form.

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