Relevant here mostly for what it no longer holds. Miscellaneous itemized deductions have been suspended since 2017, which is why the personal half of a tax preparation fee and a repayment of $3,000 or less are worth nothing rather than worth less.

Who should open it, and who should not

Schedule A is worth filling in only when its total beats your standard deduction. The instructions: "In most cases, your federal income tax will be less if you take the larger of your itemized deductions or your standard deduction."

Filing status Standard deduction, 2025 Standard deduction, 2026
Single or married filing separately $15,750 $16,100
Married filing jointly or qualifying surviving spouse $31,500 $32,200
Head of household $23,625 $24,150

Line 18 exists for the exception: you can elect to itemise even when your itemised deductions are smaller, "for state tax or other purposes."

Two groups of deductions never need Schedule A. The deductions on Schedule 1-A, such as those for tips, overtime and seniors, are claimed there whether you itemise or not. And everything that belongs to your business stays on your business schedule.

Business costs never go here

The instructions draw the line in one sentence:

"Don't include on Schedule A items deducted elsewhere, such as on Form 1040, Form 1040-SR, Schedule 1-A, or Schedule C, E, or F."

The difference is not only where an amount is written. A cost on Schedule C lowers your net profit, which lowers income tax and the 15.3% self-employment tax, and it counts whether or not you itemise. The same cost on Schedule A lowers income tax only, and only if your itemised total beats the standard deduction. Repaying income you already reported works through what that difference is worth.

Taxes are where self-employed readers most often put an amount in the wrong place:

Tax Where it goes
A state tax on gross income directly attributable to your business Schedule C
Real estate taxes on business property Schedule C
Other state and local income taxes, including estimated payments Schedule A, line 5a
Self-employment tax Not Schedule A. The deductible part goes on Schedule 1, line 15
Federal income tax Nowhere

State and local taxes: the limit on line 5e

Line 5a takes state and local income taxes or general sales taxes, "but not both." The income taxes include amounts withheld, amounts paid during the year for an earlier year, and "State and local estimated tax payments made during 2025." A payment counts in the year you make it, so a fourth-quarter state payment sent in January belongs to the next year's Schedule A. The instructions add a warning for anyone with a Form 1099-NEC that shows state tax withheld: "don't include on line 5a any withheld taxes you deducted on other forms, such as Schedule C, E, or F."

For 2025 the total of lines 5a to 5c is limited to $40,000 ($20,000 if married filing separately). Above modified adjusted gross income of $500,000, the $40,000 shrinks by 30% of the excess, though not below $10,000. Married couples filing separately start the reduction at $250,000 and take half of the result, so their limit never falls below $5,000.

Line 16: a closed list

Line 16 is not a catch-all. The instructions: "Only the expenses listed next can be deducted on line 16." The item on the list that this site's readers meet is a "Deduction for repayment of amounts under a claim of right if over $3,000."

That is why the lede above says some amounts are worth nothing rather than worth less. A repayment of $3,000 or less of income that was not business income has no line at all. The personal part of a tax preparation fee has none either: see the business split of a tax preparation fee for the part that does have a line, on Schedule C.

The lines a self-employed reader meets

Line What it asks
1–4 Medical and dental expenses, deductible only above 7.5% of adjusted gross income
5a State and local income taxes, or general sales taxes
5b State and local real estate taxes on property that is not business property
5e The limit on lines 5a to 5c
11–14 Gifts to charity. A gift of $250 or more needs the records the instructions describe
15 Casualty and theft losses from a federally declared disaster
16 Other itemised deductions, from the closed list
17 The total, carried to Form 1040, line 12e
18 The election to itemise even though the total is lower

Not every line on the schedule is covered here.

Common questions

Can I deduct my state estimated tax payments on Schedule C?
Generally not. Publication 334: "You can deduct on Schedule C (Form 1040) a state tax on gross income (as distinguished from net income) directly attributable to your business. You can deduct other state and local income taxes on Schedule A (Form 1040) if you itemize your deductions." A state income tax on your profit is the second kind.
Is self-employment tax an itemized deduction?
No. The Schedule A instructions list "Social security, Medicare, federal unemployment (FUTA), and railroad retirement (RRTA) taxes" among the taxes you can't deduct there. The deductible part of self-employment tax goes on Schedule 1, line 15, whether you itemise or not.
My business gave to a charity. Is that a business expense?
Usually not. Publication 334 lists charitable contributions among the expenses you usually can't deduct as business expenses. If you itemise, the gift goes on Schedule A, lines 11 to 14, with your other gifts to charity.
Do I have to itemise to claim the tip or overtime deduction?
No. Those go on Schedule 1-A, not Schedule A. The Schedule A instructions: "you can claim these deductions even if you itemize on Schedule A," and "you will claim these deductions on Schedule 1-A, not on Schedule A."
Why can't I deduct the personal part of my tax preparation fee here?
Because line 16 takes only a closed list, and the fee is not on it. The instructions: "Only the expenses listed next can be deducted on line 16." The part of the fee for your business schedules is a business expense on Schedule C instead.

The official page

Everything here is written from the IRS's own material, and the place to check it is Schedule A on irs.gov. Figures and rules change; the source is what settles them.

This is educational material, not tax advice. Your own situation may turn on facts this page does not know about.