My spouse received a certificate for income tax adjustment but i do not know where to enter this on the taxes

the certificate says in a prior year we were overpaid by the DoD.  the overpayment was established as a debt to the US and was reported as taxable income in that year.  The certificate certifies that during 2015 we paid the US a total of $x toward the settlement of our debt and that we can itemize this deduction and claim the repaid amount as a miscellaneous deduction.