Since you didn't use TurboTax last year, you have to tell TurboTax that you applied part or all of your 2015 refund and the amount to have this year's tax offset. You do this is the estimated taxes section. Go to Personal Fed. Taxes, then 'Deductions and Credits'. Scroll down until you see Estimates and Other Taxes Paid. Click on start next to 'Other Income Taxes'. You can enter the amount you applied to this year's taxes here.
