since repayment was in a different year you do not amend 2023. if the gross wages repaid was $3,000 or more you could take a deduction on the 2024 schedule A line 16 denoted as IRC 1341 repayment OR
recompute the taxes for 2023 by excluding the wages repaid from income. The decrease in taxes is taken as a credit on your 2024 schedule 3 line 13b
if the repayment was not net of the applicable FICA and Medicare taxes you need to file form 843 to get them refunded. see the instructions for line 7
https://www.irs.gov/forms-pubs/about-form-843
What about amounts less than $3,000?
Beginning in 2018 with the Tax Cuts And Jobs Act, miscellaneous deductions are no longer permitted. So if the amount repaid was $3,000 or less, you are not able to deduct it from your income in the year it was repaid.
