To apply last year's state refund to the current year's state tax payments in TurboTax:
- Select Federal>Deductions & Credits>Estimates and Other Taxes Paid>Other Income Taxes>Start or Revisit>click "Yes" on the "About other income taxes" screen
- Add your prior year state and local income tax refunds to "2016 Refund Applied to 2017" and continue through the interview.