How Long the IRS Has to Audit Your Tax Return

The IRS has three years from the date you file to start an audit in most cases

The statute of limitations is the legal deadline the IRS must follow. For a standard tax return with no major issues, the IRS has three years from the date you file (or the return's due date, whichever is later) to begin an audit. This means if you filed your 2021 return on April 15, 2022, the IRS generally cannot start an audit after April 15, 2025.

The three-year window is the most common rule, but it is not absolute. The deadline can be longer if the IRS finds serious problems with your return, and it can be shorter if you and the IRS agree in writing to close the case early. Understanding which timeline applies to you depends on what the IRS finds — or might find — when it reviews your return.

Key Takeaways

The IRS has three years from your filing date to start an audit for most returns, but this deadline extends to six years if you underreported income by 25 percent or more.
There is no time limit at all if the IRS suspects fraud or if you did not file a return; the agency can audit those cases indefinitely.
The statute of limitations clock starts on the later of two dates: when you actually filed or when the return was due, whichever comes second.
An audit that has already started can continue after the deadline passes, but the IRS cannot open a new audit once the statute expires.

When the deadline extends to six years

If you underreported your income by 25 percent or more, the IRS gets a longer window. The statute of limitations becomes six years instead of three. This applies to the total income you should have reported on your return. For example, if your actual income was $100,000 but you reported only $70,000, you have underreported by 30 percent, and the six-year rule kicks in.

The IRS does not need to prove fraud to use the six-year deadline — only that the underreporting was substantial. This is a civil matter, not a criminal one. The six-year clock still starts on the later of your filing date or the return's due date, just like the standard three-year rule.

Fraud and unfiled returns have no deadline

If the IRS suspects tax fraud, there is no statute of limitations. The agency can audit you at any point in the future, even decades later. Fraud means intentional wrongdoing — not mistakes or aggressive positions on a return, but deliberate misrepresentation to evade taxes. The IRS must prove fraud, which is a high bar, but when it does, time is not on your side.

The same applies if you never filed a return at all. The IRS can go back as far as it wants to assess taxes on unfiled years. If you owe taxes for multiple years and did not file, the agency can pursue all of them regardless of how long ago those years were.

How the clock starts and what pauses it

The statute of limitations begins on the later date of two: the day you actually filed your return, or the return's official due date (usually April 15 for most filers). If you file early, the clock starts on the due date, not your filing date. If you file late, the clock starts when you file. This rule prevents people from gaining an advantage by filing early.

Certain events can pause the clock. If you and the IRS sign a Form 872 (Consent to Extend the Time to Assess Tax), the deadline is extended by the period you both agree to — often six months or a year. If you file an appeal or go to tax court, the clock stops during that process. Once the appeal or court case ends, the clock resumes, but the IRS cannot assess taxes until the statute expires or you reach a settlement.

What happens if an audit is already underway when the deadline passes

An audit that has started before the deadline can continue after the statute expires. The IRS does not have to close the case on the deadline date. However, the IRS cannot propose new adjustments after the statute runs out — only finalize adjustments it already proposed before the deadline. This distinction matters because it limits what the IRS can change once time runs out.

If the IRS wants to keep investigating after the deadline is near, it will ask you to sign Form 872 to extend the statute. You are not required to sign. If you refuse, the IRS must wrap up and issue its findings before the deadline passes. Many taxpayers refuse to extend because it gives them leverage to negotiate a settlement quickly.

Different rules for amended returns and carryback claims

If you file an amended return (Form 1040-X), the statute of limitations restarts. The IRS gets three years from the date you file the amended return to audit that return, even if the original return's deadline has passed. This means amending a return can reopen the audit window.

Tax credits that carry back to prior years — such as net operating loss carrybacks — also create their own deadlines. The IRS can audit the year you claim the carryback within the normal timeframe for that year. The rules are complex and depend on the type of credit or loss involved.

Frequently Asked Questions

Can the IRS audit me after three years if I made a mistake?

A simple mistake does not extend the deadline. The three-year rule still applies unless you underreported income by 25 percent or more. If the IRS finds a mistake after three years, it cannot audit you — the statute has expired. The exception is fraud, which has no time limit.

Does filing an extension change when the statute of limitations starts?

No. Filing an extension (Form 4868) delays when your return is due, but the statute of limitations still starts on the extended due date, not your original due date. If your original due date was April 15 and you extended to October 15, the three-year clock starts on October 15.

What if I filed my return late — does the deadline change?

The statute starts on the date you actually filed, not the original due date. If you filed two years late, the three-year window begins from your actual filing date. This means the IRS has three years from when you filed, even though you were late.

Can I ask the IRS to audit me after the deadline has passed?

You can request an audit, but the IRS is not required to grant it once the statute expires. If you want to amend a return after the deadline, you can file Form 1040-X, which restarts the statute for that amended return. This is the only way to reopen a closed year.

What does it mean if the IRS sends me a notice after the statute expires?

Any notice the IRS sends after the statute expires is invalid. If you receive a notice after the deadline has passed, you can challenge it based on the expired statute. Keep records of when you filed so you can prove the deadline has passed if needed.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.