The IRS generally has three years after you file to audit your return. That window stretches to six years if you left a significant amount of income off the return, and there is no time limit at all if you filed a fraudulent return or never filed one. Which rule applies to you depends on what your return said and when it was filed.
The Standard Three-Year Window
Federal law gives the IRS three years to assess additional tax on a return you filed.1Office of the Law Revision Counsel. 26 US Code 6501 – Limitations on Assessment and Collection The clock does not start the day you submit the return. If you filed before the April deadline, the IRS treats the return as filed on the deadline itself. A return mailed on February 10 with an April 15 due date starts its three-year countdown on April 15.
Two variations change the start date. If you requested a filing extension, the three years run from the extended due date. If you filed late without any extension, the clock starts when the IRS actually received the return. The practical effect is that a return filed in early February can still be audited nearly four years later, because the statute did not begin ticking until mid-April.
When the Window Extends to Six Years
The IRS gets six years when a taxpayer omits from gross income an amount exceeding 25% of the gross income shown on the return.1Office of the Law Revision Counsel. 26 US Code 6501 – Limitations on Assessment and Collection This rule targets income left off the return entirely. Inflated deductions and miscalculated credits do not trigger it.
The math: if your return shows $80,000 in gross income, 25% is $20,000. If you actually earned $107,000 and left off $27,000, you crossed the threshold and the IRS has six years to catch it. The benchmark is 25% of what you reported, not 25% of what you actually earned.
A separate trigger applies to foreign financial assets. If you omit more than $5,000 of income tied to assets that should be reported under FATCA, the six-year window opens even if the omission is nowhere near the 25% threshold.1Office of the Law Revision Counsel. 26 US Code 6501 – Limitations on Assessment and Collection This concerns unreported income from foreign assets, not the value of the assets. FATCA’s asset reporting thresholds start much higher, at $50,000 for domestic filers, but the audit extension itself triggers at just $5,000 of omitted income.2Internal Revenue Service. Summary of FATCA Reporting for US Taxpayers
When There Is No Deadline at All
The statute of limitations disappears in two situations: a fraudulent return filed with intent to evade tax, or a year for which you never filed a return.1Office of the Law Revision Counsel. 26 US Code 6501 – Limitations on Assessment and Collection
Fraud means a willful attempt to cheat, not a careless math error or a misunderstood rule. The IRS carries the burden of proving intent, and that bar is high. Once cleared, though, the door to that return stays open indefinitely.
Not filing is the more common route to unlimited exposure. If you skip a tax year, the three-year clock never starts, because there is no return to trigger it. The IRS can come after that year a decade or two later without any statute of limitations problem.
Being Asked to Extend the Deadline During an Audit
If the IRS is examining your return and the three-year window is about to close, the agent will often ask you to sign Form 872, extending the assessment period to a specific future date. Audits are slow, and the IRS frequently cannot finish before time runs out.
You have the legal right to refuse. You can also ask that the extension cover only specific issues or last only until a certain date, and the IRS must inform you of these rights each time it makes the request.1Office of the Law Revision Counsel. 26 US Code 6501 – Limitations on Assessment and Collection The right is to request a limited extension; the IRS can decline and insist on a broader one.3Internal Revenue Service. 25.6.22 Extension of Assessment Statute of Limitations by Consent
Refusing carries a predictable cost. When a taxpayer declines to extend, the IRS typically issues a deficiency notice based on whatever incomplete information it has, and that notice tends to be less favorable than the outcome of a fully developed audit. Many tax professionals recommend signing while negotiating to narrow the scope.
The Separate 10-Year Collection Clock
Once the audit ends and the IRS formally records what you owe, a new 10-year period begins for collecting it.4Office of the Law Revision Counsel. 26 USC 6502 – Collection After Assessment This clock is separate from the audit clock. Assessment (three years, six years, or unlimited) governs how long the IRS has to determine you owe more; collection (10 years) governs how long it has to pursue the balance through liens, levies, and wage garnishments. After 10 years, the debt becomes legally unenforceable.
Certain actions pause the collection clock and push the expiration date back: filing bankruptcy, submitting an offer in compromise, requesting an installment agreement, or living outside the United States for six or more consecutive months. If you owe a significant balance, the actual expiration date can sit well past the nominal 10-year mark.
How Long to Keep Your Tax Records
Record retention should track the audit window that could apply to you. The IRS recommends keeping tax records for at least three years from the date you filed, which matches the standard assessment period.5Internal Revenue Service. How Long Should I Keep Records Several situations call for longer:
- Six years if there is any chance you underreported income by more than 25% of what your return showed.
- Seven years if you claimed a loss from worthless securities or a bad debt deduction.
- Four years for employment tax records, measured from the date the tax was due or paid, whichever is later.6Internal Revenue Service. Recordkeeping
- Indefinitely if you did not file a return or filed a fraudulent one.
Property records are a separate case. Keep documentation of your purchase price, improvements, and depreciation until the limitations period expires for the year you sell or dispose of the property.5Internal Revenue Service. How Long Should I Keep Records
State Audits Run on Their Own Clock
These rules govern the IRS only. State revenue agencies operate under their own statutes of limitations, usually three or four years, though the specifics vary. Some states tie their deadline to the federal one so a federal extension automatically extends the state window; others run independently. Check your state’s department of revenue for the rules that apply to returns filed there.