It's not an excess withdrawal. An RMD is a minimum withdrawal, but you can withdraw as much as you want in addition to the RMD. Your Form 1099-R for 2023 should show the total amount that you withdrew in 2023, including both your 2023 RMD and the make-up withdrawal for the 2022 RMD. All you have to do is enter the amount shown on the 1099-R. It doesn't matter how much was for the late 2022 RMD and how much was for 2023. You do not have to show the amounts separately or explain the amount.