Hi, my employer is asking metro return $20K bonus that I received last year and it is repayable if I leave before year end. I received only the net amount after taxes and already filed taxes for last year. My employer says I need to return the gross amounts but they will not issue a revised W-2. How do I get the taxes back? Thanks.

If you return the bonus, the employer should debit your current year pay for the amount being returned. Make that a condition of you returning the bonus.