How Long Does the IRS Have to Audit Your Return?

The IRS generally has three years from the date you filed your return to audit it and assess more tax. That covers most taxpayers in most years. But the deadline stretches to six years when a return leaves off a significant amount of income, and it disappears entirely if you never filed or if the IRS can prove fraud. So the honest answer to how long the IRS has to audit your return is: it depends on what the return looks like.

The Three-Year Default

Federal law gives the IRS three years after a return is filed to review it and assess any additional tax.¹ This is the rule that applies to most individual and business returns when nothing unusual is going on.

When the clock actually starts depends on when you filed. File early, and the IRS treats your return as filed on April 15, so the three years run from the deadline rather than the day you sent it in.¹ File on an extension in October, and the clock starts on the date the IRS actually receives the return.

Once those three years pass, the IRS loses the authority to come back for more tax on that year. A deduction the agency might have questioned but never examined in time simply stands.

When the Window Extends to Six Years

The audit deadline doubles to six years when a return omits a large amount of income. The trigger is specific: the missing income must exceed 25 percent of the gross income you actually reported.¹ If your return showed $100,000 in gross income but you really earned $130,000, the $30,000 gap crosses the threshold and the IRS gets six years.

The rule also captures overstated cost basis on assets you sold. Inflating basis reduces the reported gain, and the law treats that the same as omitting income.¹ If the understatement crosses 25 percent, the six-year window applies. This surfaces most often in real estate sales and inherited property, where basis calculations get complicated.

Estate and gift tax returns follow the same pattern. An estate return that omits items exceeding 25 percent of the reported gross estate, or a gift tax return that understates gifts by that margin, gets six years of exposure instead of three.¹

When There Is No Deadline at All

Two situations remove the audit deadline completely.

The first is failing to file. If you never filed a return for a given year, the statute of limitations never starts running. The IRS can assess taxes for that year at any point, whether five, ten, or thirty years later.¹

The second is fraud. If you filed a false or fraudulent return with intent to evade tax, the IRS can audit and assess at any time, no matter how many years have passed.¹ Fraud cases usually involve deliberate acts: hiding income in unreported accounts, fabricating deductions, using false Social Security numbers. The IRS bears the burden of proving fraudulent intent, and that is a high standard. Math errors, even large ones, are not fraud. But when the agency meets that burden, the passage of time offers no protection.

Foreign Assets Keep the Window Open Longer

Holding accounts or assets outside the United States triggers extra rules that can push the audit window well past three years.

The six-year window applies when you omit more than $5,000 in income tied to foreign financial assets that should have been reported on Form 8938. Unlike the general substantial-omission rule, this is a flat dollar threshold, not a percentage, so it is much easier to trip.¹

More significantly, if you fail to file a required foreign information return (Forms 8938, 5471, 3520, and others), the three-year assessment period does not begin running on the related tax return until three years after you actually provide the required information.¹ In practical terms, the audit window stays open indefinitely until you file the missing form.

FBAR penalties run on a separate track. The IRS has six years from the FBAR’s due date (April 15 for tax years 2016 and later) to assess civil penalties for failing to file. The automatic six-month FBAR filing extension does not push out that penalty deadline, and a consent extending your income tax audit does not extend it either. A separate FBAR consent is required.²

Does Filing an Amended Return Restart the Clock

No. Filing an amended return on Form 1040-X does not restart or extend the original three-year deadline for that tax year.³ The assessment clock keeps running from the date the original return was filed (or from the April 15 deadline, if you filed early).

There is one narrow exception. If the IRS receives your signed amended return within the last 60 days before the original deadline expires, the agency gets an additional 60 days, but only to assess the extra tax reported on the amendment itself. It does not reopen the whole return.³ The extension applies to income taxes only, not employment or excise taxes. And an amended return filed before the original filing deadline just replaces the original and does nothing to the audit timeline.

When the IRS Asks You to Sign an Extension

When an audit is still in progress and the deadline is closing in, the IRS will often ask you to voluntarily extend it. You can refuse.⁴

Two forms do this work. Form 872 sets a specific future date when the extended deadline expires. Form 872-A creates an open-ended extension that stays in place until you or the IRS acts to end it.⁵ Form 872 is generally the safer choice for taxpayers because both sides have a clear endpoint.

There are practical reasons to agree. Extending gives the examiner time to finish reviewing your records, which can produce a more accurate and sometimes more favorable outcome. Refuse, and the IRS will typically issue a statutory notice of deficiency based on whatever information it has, which may propose a larger tax increase than a completed audit would have.⁶ That notice gives you 90 days to petition the U.S. Tax Court if you disagree with the amount.⁷

How Long to Keep Records

Your record-keeping should match the longest audit window that could apply. The IRS recommends keeping records as long as they may be needed to support items on a return, which in practice means at least as long as the statute remains open.⁸

Three years is the minimum for most taxpayers. Hold income statements, receipts for deductions, and supporting documents at least that long after filing.
Six years covers the risk of unintentional income underreporting during the extended audit window.
Seven years applies if you claimed a bad debt or worthless securities deduction, since a refund claim on those items has a longer window.⁸
Property records (purchase price, improvements, depreciation) should be kept until at least three years after you sell the property, because you need them to calculate gain or loss. If you never filed for a particular year, keep those records permanently.

State income tax deadlines vary. Most states follow a three- to four-year audit window that generally mirrors the federal one, and some states automatically extend their deadline whenever the IRS adjusts a federal return. Keeping records for the federal period typically covers the state period as well.

The Audit Clock Is Not the Collection Clock

One clarification worth keeping straight: the deadline to audit and the deadline to collect are two separate clocks. Once the IRS finishes an audit and formally assesses tax, a new 10-year window opens for actually collecting the money.⁹ That period is called the Collection Statute Expiration Date, or CSED, and several actions (installment agreements, offers in compromise, bankruptcy, collection due process hearings, innocent spouse claims) can pause it.¹⁰ So even if the audit deadline passes, an assessment already on the books can still be collected for years afterward.

1
Office of the Law Revision Counsel. 26 USC 6501 Limitations on Assessment and Collection
2
Internal Revenue Service. FBAR Penalties
3
Internal Revenue Service. Statute of Limitations Processes and Procedures
4
Internal Revenue Service. Taxpayer Bill of Rights
5
Internal Revenue Service. Extending the Tax Assessment Period
6
Internal Revenue Service. Extension of Assessment Statute of Limitations by Consent
7
Internal Revenue Service. Understanding Your CP3219N Notice
8
Internal Revenue Service. Topic No. 305, Recordkeeping
9
Office of the Law Revision Counsel. 26 USC 6502 Collection After Assessment
10
Internal Revenue Service. Time IRS Can Collect Tax