If a payer withholds from a payee in error or withholds more than the correct amount of tax, the payer may refund the amount improperly withheld. The refund must be made prior to the end of the calendar year and prior to the time the payer issues a Form 1099. If the payer has not deposited the amount of the tax prior to the time that the refund is made to the payee, the payer should not deposit the improperly withheld tax. If the improperly withheld tax has been deposited prior to the time the refund is made to the payee, the payer may adjust any subsequent deposit of tax collected, which the payer is required to make, by the amount of the tax which has been refunded to the payee. Payers may use refund alternatives only when backup withholding is the result of an error by the payer. The timely submission of requested TIN information including any verifications and/or certifications by the payee does not establish an error by the payer.
For additional information see Publication 1281, Backup Withholding.