Taxpayers who have overpaid can choose to:
A field in the signature section at the bottom of Form 1040 labeled Identity Protection PIN is designed to help prevent refunds from being issued to an identity thief. See Form 1040 Instructions for more information.
For taxpayers who want to apply a portion of the overpayment to next year's taxes, enter the amount to be applied to the following year on the applicable line. By entering an amount on this line, the taxpayer is electing to apply all or a portion of the current year's overpayment to next year's estimated tax.