If you receive a refund of (or credit for) state or local income taxes in a year after the year in which you paid them, you may have to include the refund in income in the year you receive it. This includes refunds resulting from taxes that were over withheld, applied from a prior year return, not figured correctly, or figured again because of an amended return. If you did not itemize your deductions in the previous year, do not include the refund in income. If you deducted the taxes in the previous year, include all or part of the refund in the year you receive the refund.

This information is found in Publication 525, Taxable and Nontaxable Income.