IRS Form 1040 “U.S. Individual Income Tax Return” Explained

IRS Form 1040, U.S. Individual Income Tax Return, is the main federal income tax return for individuals. It brings together your income, adjustments, deductions, credits and payments to figure whether you owe tax or get a refund. Taxpayers 65 or older can use Form 1040-SR, which has the same lines in larger print.

Who Must File

Whether you must file depends on your filing status, age and gross income. In general, you must file if your gross income is more than your standard deduction. You must also file in certain other cases, such as when you have $400 or more of self-employment income, owe special taxes, or received advance premium tax credit payments. Even if you aren’t required to file, you should file to claim a refund of withholding or refundable credits.

How the Return Flows

1. Filing status and dependents: single, married filing jointly, married filing separately, head of household, or qualifying surviving spouse
2. Income: wages, interest, dividends, IRA and pension distributions, Social Security, capital gains, and other income from Schedule 1
3. Adjustments: such as deductible IRA and HSA contributions, half of self-employment tax and student loan interest, which give you your adjusted gross income (AGI)
4. Deductions: the standard deduction or itemized deductions, the qualified business income deduction, and new deductions on Schedule 1-A, which give you taxable income
5. Tax and credits: tax from the rate tables, plus additional taxes from Schedule 2, minus credits such as the child tax credit and those on Schedule 3
6. Payments: withholding, estimated payments and refundable credits, which give you your refund or balance due

2026 Figures

• Standard deduction: $16,100 single, $32,200 married filing jointly, $24,150 head of household, according to the IRS
• Tax rates: seven brackets from 10% to 37%. The 10% bracket covers taxable income up to $12,400 single or $24,800 joint.
• New deductions for 2025-2028 (Schedule 1-A): qualified tips (up to $25,000), qualified overtime pay (up to $12,500, or $25,000 joint), interest on a loan for a new U.S.-assembled personal vehicle (up to $10,000), and an extra $6,000 deduction for each taxpayer age 65 or older. Each is subject to income phase-outs. You can claim them whether or not you itemize.

Deadlines

Form 1040 is generally due April 15. You can get an automatic six-month extension to October 15 with Form 4868, but an extension to file isn’t an extension to pay. Pay what you expect to owe by April 15 to limit penalties and interest. If you can’t pay in full, see What to Do If You Can’t Pay Your Taxes.

Get Help From Diehl CPA

Tax rules change often, and the right answer depends on your full financial picture. Diehl CPA, led by Mark Diehl, CPA, CFE, prepares returns and builds tax plans for investors, retirees and closely held businesses. Learn about our tax return preparation and investment tax planning services, or contact us to talk through your situation.

This article is general information, not tax or legal advice for your specific situation. Updated October 2026.