Updated October 18, 2026. Quick answer: Line 5a is where you enter either your state and local income taxes or your state and local general sales taxes. The form lets you pick one, not both, and a box on the line is checked if you pick sales taxes. The amount comes from your withholding and payments, or from actual receipts or the IRS optional tables.
What line 5a asks for
The form’s caption reads “State and local income taxes or general sales taxes.” “You may include either income taxes or general sales taxes on line 5a, but not both.” “If you elect to include general sales taxes instead of income taxes, check this box”. The instructions repeat it: You “can elect to deduct state and local general sales taxes instead of state and local income taxes.” “You can’t deduct both.”
Line 5a is the first of three lines that together make up the state and local tax total. See Schedule A lines 5d and 5e for how lines 5a to 5c are added and limited, and Schedule A lines 5b and 5c for the property tax lines.
If you use income taxes
The instructions say “include on line 5a the state and local income taxes listed next.” The first item is “State and local income taxes withheld from your salary during 2025.” They add that “Form(s) W-2 will show these amounts.” The second is “State and local income taxes paid in 2025 for a prior year”, and the instructions add “Don’t include penalties or interest.” The third is “State and local estimated tax payments made during 2025”.
The instructions also say what not to subtract: “State or local income tax refund or credit you expect to receive for 2025”. Your federal estimated payments are a different matter and are covered on the Form 1040-ES page.
If you use general sales taxes
The instructions say “If you elect to deduct state and local general sales taxes instead of income taxes, you must check the box on line 5a.” They describe the two ways to figure it: “you can use either your actual expenses or the optional sales tax tables.”
For actual expenses, the instructions say you “must keep your actual receipts showing general sales taxes paid to use this method.” For the optional route, use the state and local general sales tax deduction worksheet and the tables at the end of the instructions; their figures are not repeated here, so read them in the instructions for your state and income.
The instructions also exclude one kind of purchase: “Don’t include sales taxes paid on items used in your trade or business.”
Where the number comes from
For income taxes, add the withholding shown on your Forms W-2, the prior-year balance you paid in 2025 and your 2025 estimated payments, using the list above. For sales taxes, the figure is the result of your actual receipts or the worksheet. Whichever you choose, the same amount is entered once on line 5a.
Where it goes next
Line 5a is added with lines 5b and 5c. The form says “Add lines 5a through 5c” on line 5d. See Schedule A lines 5d and 5e for line 5d and the limit that follows it. The schedule is introduced on the Schedule A (Form 1040) page, and the return it attaches to is explained on the Form 1040 page.
Edition and line numbers
This page reads the 2025 Schedule A (Form 1040) and its 2025 instructions, the current files irs.gov served on 2026-10-18 (byte-identical to the archived copies). They are the files for the tax year 2025 return, filed in 2026. The schedule says “Attach to Form 1040 or 1040-SR.” Check the tax year printed on the schedule you are filling in and use the line numbers on that year’s schedule, because a different year’s schedule can number or word its lines differently.
Common mistakes
- Entering both kinds of tax. The form says “You may include either income taxes or general sales taxes on line 5a, but not both.”
- Choosing sales taxes and forgetting the box. The instructions say “you must check the box on line 5a.”
- Adding penalties or interest to the income tax total. The instructions say “Don’t include penalties or interest.”
Related: Form 1040 line 12, Form 1040-ES, Form 1040 lines 9, 10 and 11, and Schedule A (Form 1040).
Sources
- Instructions for Schedule A (Form 1040), Itemized Deductions (2025): https://www.irs.gov/pub/irs-pdf/i1040sca.pdf
- Schedule A (Form 1040), Itemized Deductions (2025): https://www.irs.gov/pub/irs-pdf/f1040sa.pdf
Read from the IRS documents linked above on October 18, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.