Depends:
Simple answer...only the state taxes paid to the state during 1 Jan to 31 Dec 2017, plus all state withholding counts.
So if you made a 4th Quarter payment to the state in Jan of 2018, that is a credit on state taxes for your 2017 state tax return, but it isn't a deduction for 2017 Federal taxes. IF you paid it in December of 2017..you need to indicate that as the default is the Jan 2018 date.
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Additional Info: On the plus side, if you paid a balance due to the state during 2017 for 2016 state taxes, or a a state extension payment last year, you can add those in as a Federal deductions for 2017....or if you made a 4th quarter payment to the state in Jan of 2017 (for 2016 state taxes) you can include that as a federal deduction
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
