Form 1040 is a federal tax form. It is issued by the IRS and used to report income and calculate tax owed to the U.S. government, not to any state. If you live in a state that collects income tax, that return is filed separately with your state’s own revenue department on a form the state itself creates.1Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return
What Form 1040 Does at the Federal Level
Form 1040 is the standard individual income tax return the IRS uses to collect federal income tax. On it, you report wages from W-2s, self-employment earnings, taxable interest, qualified dividends, and retirement distributions.1Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return Federal law requires anyone whose gross income meets or exceeds certain thresholds to file it.2Office of the Law Revision Counsel. 26 USC 6012 – Persons Required to Make Returns of Income
The same form is where you claim federal credits and deductions. The Child Tax Credit and Earned Income Tax Credit reduce your federal tax directly, while above-the-line deductions for student loan interest, educator expenses, and retirement contributions lower the income the federal rate is applied to.1Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return For most individual filers, no other federal form is needed. Everything about your federal income tax obligation is handled here.
Whether you have to file depends on gross income compared to the standard deduction for your filing status. For tax year 2026, the standard deduction amounts are:3Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- Single or married filing separately: $16,100
- Married filing jointly or surviving spouse: $32,200
- Head of household: $24,150
Taxpayers 65 or older get a higher threshold thanks to an additional standard deduction amount.2Office of the Law Revision Counsel. 26 USC 6012 – Persons Required to Make Returns of Income If your income falls below the applicable amount, filing is generally optional, though it can still be worth doing if you had tax withheld or qualify for a refundable credit.
State Income Tax Uses a Different Form
State income taxes are not part of Form 1040 and are not processed by the IRS. Each state that collects an income tax runs its own revenue department, creates its own return, and sets its own rules. The form name and number vary by state. You submit that return to the state, not to the IRS.
Nine states do not impose a broad individual income tax at all. Residents there file only the federal Form 1040 for wage and salary income and have no state return to worry about. In the remaining states and the District of Columbia, a state return is filed alongside the federal one.
If you earn money in a state you do not live in, that state may also want a nonresident return. The trigger differs a lot: some states require a return if you worked there for a single day, while others set a minimum income or day-count threshold before a filing obligation kicks in. Check the rules of any state you earned money in, not just the state you live in.
How the Federal and State Returns Connect
Although filed separately, the two returns are linked through one number. Your Adjusted Gross Income — the figure on line 11 of Form 1040 — is the starting point most states use to calculate state taxable income. AGI is your total income after above-the-line deductions like student loan interest, educator expenses, and IRA contributions.1Internal Revenue Service. About Form 1040, U.S. Individual Income Tax Return From there, states apply their own additions and subtractions to reach the amount they tax.
Because of that dependency, the IRS recommends completing your federal return before starting a state return. It also means changes on one side flow to the other. If the IRS adjusts your federal return later, your state taxable income usually changes too, and most states require you to report federal changes within a set window (often 60 to 180 days, depending on the state) and file an amended state return with the new figures.
Deadlines to Know
The federal Form 1040 for tax year 2025 is due April 15, 2026, and any tax owed is due that day as well.4Internal Revenue Service. IRS Opens 2026 Filing Season Most states with an income tax use the same date, but some use different deadlines, so confirm with your state.
If you need more time, filing Form 4868 with the IRS gives you an automatic six-month extension to file, pushing the federal deadline to October 15, 2026.5Internal Revenue Service. Application for Automatic Extension of Time to File U.S. Individual Income Tax Return The extension is to file, not to pay; the balance is still due April 15, and interest and penalties start running the day after. Many states grant an automatic state extension when you file a federal one, but some want their own extension form or a payment voucher if state tax is owed. Read your state’s rules before assuming the federal extension covers you.