Schedule A line 5a calculation - deduction for state income taxes paid

[fmlybdgt]

I'm itemizing deductions and married filing jointly, because of higher SALT limit itemizing is favorable for me.  Once completely done with TT entry questionnaire, I compared all values to my own calcs and found the deduction amount for state and local taxes pd didn't match - TT calculated $5 lower than me.  Sources include state withholdings from two W2s and the state tax return amount due for 2024 tax year that I pd in 2025 ($219), so only 3 values.  I have other SALT items that report on lines 5b and 5c and those are calculating fine.  The total value on 5d is around $27,000, so not over the limit.

By experimentally changing them each to zero on their respective input fields I was able to determine that TT is not including the total amount of the 2024 state tax return amt due and pd in the deduction total, but the 2 W2 values are being included properly.  In doing these tests I need to force TT to still calculate with itemized deductions instead of switching to standard deduction of course.  When this state return value is the only input provided, the total deduction for line 5a calculates to $213 ($6 short).  When this state return value is included with one of the W2 withholding values, the deduction calculates $6 short.  And when this state return value is included with both W2 values the deduction calculates $5 short.  What's going on? 

[VolvoGirl]

Could you have had a penalty on the state return?  Double check your 2024 state return.  And 6 vs 5 could be from rounding.

[fmlybdgt]

Yes understood about rounding.  Having it not be the full value is the mystery.  Previous state return was efiled by TT and still shows as accepted in my TT acct with the same amt due and pd as I have entered into the software this year.  No follow up mailings from the state about rejections or penalties.

[fmlybdgt]

New info:  Another test:  There a state tax refund reported in the income section.  I changed it to zero, and saw the schedule A line 5a was then calculating the full deduction value for the state taxes paid.  What's strange though is that this means TT is treating the state tax refund as taxable in some way, but it shouldn't- because the refund was received in 2025 for the 2024 tax year, and for that tax year I filed with the standard deduction.  And according to TT's own questionnaire when I enter this refund on the income section, it says congratulation this refund is not taxable.  And all other resources I find says state tax refunds attributable to a tax year where the standard deduction was used are not taxable if you itemize the following year.  So still it means the TT calculation of line 5a on Schedule A seems to be incorrect math.