Further question: How do you actually amend a 2020 return to show the repayment?

Taxpayer repaid the entire amount in 2022. Since the distribution was spread over three years, there would not be anything included in the 2022 return but need to carry back the excess repayment to 2021 and 2022. This is the amended return for 2020 and 2021.

But, what part do you actually amend?

81915E has line 10 but its for repayment before the due date of the return and specifically states not to include repayments made later than the due date.

So, where do you put the repayments made after the due date of the return when amending?