You may be able to get at least part of the tax paid refunded. Here is a link to Publication 525. See pages 34-35 about how to handle a repayment. You must re-figure your taxes for the prior year without the bonus income and compare that to the taxes in the current year without the bonus. You may be able to use either a deduction in the current year (if the amount repaid is over $3000) or a credit.
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