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This is the scenario...

My husband paid back the sign-on bonus of 5K within the same year he received the bonus, which included about $1,400 in taxes. He received his W2 which first did not include the payback within the same year and we just received the corrected W2 and when entering the new numbers our refund only went up $300 instead of the $1,400 that he paid last year. Why isn't he getting back the same amount he paid back in taxes?