Signing bonus

My husband received a sign-on bonus in 2021 ($6,000).  He left before the contract ended in 2022.  We repaid the gross amount of $6,000 in 2023 even though net total was approx. $3,400.  A corrected W-2c has been received from the employer reflecting the withholding in boxes 3, 4, 5, and 6 which is for the FICA taxes.  The employer did refund the FICA taxes withheld for the bonus.  

 

I am not sure how to recoup the taxes federal and state taxes withheld on the $6,000 bonus repaid in 2023.  Since the corrected W-2 does not change the wages or state and federal withholding it seems a corrected 1040 for 2021 is not the correct way to proceed.

 

Please advise.  All help is appreciated!