Whether you must file a U.S. federal tax return depends on who you are, not on whether you own a company. Individuals file when their income passes a threshold or when they have U.S. income as a non-resident. Corporations and most partnerships file every year, even with no income. Every return needs a tax number: an SSN or ITIN for a person, an EIN for a business.
Individuals
- U.S. citizens and resident aliens file Form 1040 when their gross income is above the filing threshold for their age and filing status. The thresholds change every year; the IRS has an online tool that tells you whether you need to file.
- Self-employed people file when their net earnings from self-employment are $400 or more, whatever their other income. See self-employed tax obligations.
- Non-resident aliens file Form 1040-NR when they are engaged in a trade or business in the U.S., or have U.S. income on which the tax was not fully withheld.
A person who has to file and cannot get a Social Security number files with an ITIN. The first time, Form W-7 is attached to the return itself. See our ITIN application service.
Companies
- Corporations file Form 1120 every year, whether or not they have income.
- Partnerships and multi-member LLCs file Form 1065, and give each partner a Schedule K-1.
- Single-member LLCs owned by a U.S. person are reported on the owner's own return, normally on Schedule C.
- Single-member LLCs owned by a foreign person file a pro forma Form 1120 with Form 5472 attached. The penalty for not filing Form 5472 on time is $25,000.
The Main Forms
| Form | Who uses it |
|---|---|
| Form 1040 and 1040-SR | U.S. citizens and resident aliens; 1040-SR is the version for people aged 65 or over |
| Form 1040-NR | Non-resident aliens |
| Schedule C | Profit or loss of a sole proprietor or single-member LLC |
| Schedule SE | Self-employment tax |
| Schedules A, B and D | Itemized deductions; interest and dividends; capital gains and losses |
| Form 1120 and 1120-S | Corporations and S corporations |
| Form 1065 | Partnerships and multi-member LLCs |
| Form 5472 | Foreign-owned U.S. corporations and single-member LLCs |
| Form 4868 and Form 7004 | More time to file, for individuals and for businesses |
| Form 1040-X | Correcting a return that was already filed |
Forms W-2, 1098 and 1099 are not returns you file: employers, lenders and clients send them to you, and you use the figures on your return.
When Returns Are Due
For a calendar year: March 15 for partnerships and S corporations, April 15 for individuals and corporations, and June 15 for non-resident aliens who had no wages subject to U.S. withholding. A date that falls on a weekend or holiday moves to the next business day.
Not sure which number you need before you can file? See ITIN vs EIN.
Source: IRS, Check if you need to file a tax return; IRS, Taxation of nonresident aliens; IRS, Instructions for Form 5472. Checked October 2026.
