Do I have to file a US tax return?

Most people must file when gross income for the year passes the threshold for their filing status, age, and dependent status. Self-employment is the trap: a much lower threshold applies to net earnings from self-employment, so a small side business can create a filing requirement even when total income is well under the ordinary threshold. Filing can also be worthwhile to claim a refund.

For tax year 2025

$400 (self-employment tax filing threshold, 2025)

Key points

The general federal filing requirement is a gross income threshold set by filing status, age, and whether the person is claimed as a dependent, and it is adjusted each year — dependents have their own, much lower thresholds.
Net earnings from self-employment create a filing obligation at a much lower threshold than the general one, so a small side business can require a return on its own.
Filing is often worthwhile even when no return is required, because withheld tax and refundable credits are only paid out on a filed return.
Residency for tax purposes decides whether a person files the standard individual return or the nonresident return, and it is a separate question from immigration status.
A required year that was never filed stays due, with the failure-to-file penalty and interest running from the original due date.

What is the general threshold for having to file?

The ordinary filing requirement is a gross income test set by filing status, age, and whether you are claimed as a dependent on someone else's return — dependents have their own, much lower thresholds. It is adjusted each year, and for most people it tracks the standard deduction available to their status. Someone whose income for the year stayed below it, with nothing unusual in the year, generally has no filing obligation.

Certain items override the threshold entirely. Owing a special tax, receiving advance credit payments that must be reconciled, or holding income that carries its own reporting duty can each require a return no matter how small the year's total was.

Why does self-employment change the answer?

Because the self-employment threshold is separate and far lower. Net earnings from self-employment of at least a small annual amount create a filing requirement on their own, since self-employment tax — the Social Security and Medicare tax a self-employed person pays on both the employee and employer side — is owed on those earnings independently of income tax.

This is where first-time filers get caught. A person with a modest wage job and some freelance, consulting, delivery, or platform income can be required to file even though the year's total income never approached the ordinary threshold. The trigger is the business earnings, not the size of the year.

Should you file even when you are not required to?

Often, yes. Tax withheld from wages is not returned automatically; it comes back only when a return is filed. Refundable credits work the same way — they are claimed on a return, and a person who files nothing claims nothing. Someone under the threshold who had tax withheld during the year is usually leaving a refund unclaimed.

There is also a documentation reason. A filed return is the record that lenders, immigration processes handled by an attorney, and licensing bodies frequently ask for, and reconstructing an unfiled year later is harder than filing it on time.

What if a year that should have been filed was skipped?

It stays open. The return remains due, and both the failure-to-file penalty and interest run from the original due date without extensions, which is generally mid-April. Nothing about the passage of time removes the obligation, and the balance grows while the year sits unfiled.

Filing the late return is the step that stops the faster of the two penalties from accruing further, even when the tax cannot be paid at the same time. First-time penalty relief exists, and the IRS can abate a late-filing or late-payment penalty where there is reasonable cause and the failure was not willful neglect. Interest is generally not abated and continues until everything assessed is paid.