@Canonical
State income tax deductions on the Federal Schedule A, will only include state income taxes paid during calendar year 2025.
Thus if you make a final State Tax due payment now, in 2026, that isn't included in the Sched A , line 5a.
BUT, if you do make a State tax due payment now (in 2026) ...it can be included in the 2026 Federal Schedule A next year...along with any state withholding done during 2026.
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IF you had a final State tax due on your 2024 State tax return, that you filed in 2025...that amount you paid to the state can be included in the Schedule A. line 5a value....but you have to make sure you entered that amount in the Federal section.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
