When you receive a state or local tax refund of taxes that were included in Sch A in the prior year and were also subject to AMT, you recompute that prior year's income tax liability with the deduction reduced on Sch A by the amount of the refund you received. If the resulting recomputed tax is lower or is unchanged, there was no tax benefit. If the resulting recomputed tax is higher, as it is in your client's case, then the difference between the amount of total tax on the return as filed and the recomputed tax liability is the amount of the tax benefit that was derived by the deduction on that prior year's return, and is the amount of the refund that is taxable. Example with made up numbers: Client's 2013 Sch A included $68K in state taxes paid. Client's total tax liability for 2013 including AMT is $180,000. In 2014 $61K of state tax is refunded. Recompute tax with only $7K of the state tax on Sch A (the 68K tax paid minus the refunded portion) and now total tax liability as recomputed is $180,018. Because the resulting tax would have been $18K higher, the client received a tax benefit of $18K on the 2013 return as a result of that state tax deduction that was refunded in 2014, and therefore in this example, $18K of the state refund is taxable in 2014.