IRS Audit Statute of Limitations: 3, 6, or Unlimited Years

The IRS audit statute of limitations is three years from the date you file your return in most cases, six years if you omitted more than 25% of your gross income, and unlimited if you filed a fraudulent return or never filed at all. Those three windows cover almost every situation, and which one applies to you determines how long you stay exposed and how long you should hold onto your records.

The Three-Year Default

The standard rule is simple. The IRS has three years after you file a return to assess additional tax for that year. Once those three years pass, the agency loses its power to change what you owe, even if it later catches an honest mistake.¹

When the clock starts depends on when you filed. File early, in February say, and the clock still doesn’t start until the actual due date. The law treats an early return as filed on the deadline, typically April 15.¹ For the 2025 tax year, the deadline is April 15, 2026, so the IRS has until April 15, 2029 to audit a return filed on or before that date.²

File late, after the deadline and any extension, and the three years run from the day the IRS receives your return. Late filing doesn’t shorten the window; it shifts it forward.

Mailing Date Counts as Filing Date

If you mail a paper return, the postmark is your filing date, not the day the IRS opens the envelope. This applies to U.S. Mail and to designated private carriers like FedEx and UPS. Certified or registered mail gives you a registration date as proof of when you sent it.³ If a dispute ever arises about timing, that postmark controls which clock applies.

Six Years for Large Income Omissions

The IRS gets six years when you leave a large chunk of income off your return. The trigger: the omitted amount exceeds 25% of the gross income you actually reported. So if your return shows $100,000 in gross income and you failed to report another $30,000, the six-year window applies, because $30,000 exceeds 25% of $100,000.¹

The rule targets income that was left off the return entirely. Overstating deductions or inflating charitable contributions, on its own, doesn’t extend the period unless the effect is equivalent to omitting gross income.

Basis Overstatements Count

If you sell property and inflate your basis, you reduce the taxable gain you report. Congress made clear in 2015 that an understatement of gross income caused by an overstatement of basis counts as an omission from gross income for the six-year rule.¹ Overstate your basis enough to shave more than 25% off your total gross income, and the IRS has six years, not three. Disclosing the basis calculation on your return doesn’t get you out of it either; the statute specifically removes that escape hatch for basis overstatements.

Foreign Accounts and Assets

Offshore reporting comes with its own extended timelines, and taxpayers often assume the standard three-year rule covers them when it doesn’t.

Omit more than $5,000 in income from a foreign financial asset that should have been reported on Form 8938, and the IRS gets six years to audit that return, even if the omission is well under the usual 25% threshold.⁴

If you were required to file Form 8938 and didn’t, the assessment clock for your income tax return doesn’t start at all. The IRS can audit you at any time until you file it. Once you file a complete and accurate Form 8938, the normal three-year period runs from that point. If the failure was due to reasonable cause rather than willful neglect, only the issues tied to the unreported foreign information stay open, not the whole return.⁴

FBAR filings (FinCEN Form 114) run on their own six-year assessment clock for penalties, separate from your income tax return.⁵

When There Is No Time Limit

Several situations remove the statute of limitations entirely. The IRS can come after you five, ten, or thirty years later.

Fraudulent Returns

File a false or fraudulent return with intent to evade tax, and there is no deadline for the IRS to act. The clock never starts.¹ On top of the tax owed, the civil fraud penalty is 75% of the underpayment attributable to fraud.⁶ The IRS carries the burden of proving fraud, but it can build a case years later using third-party records, bank data, and lifestyle analysis.

Never Filing at All

If you never file a return, the statute of limitations never begins. The IRS can assess the tax at any time, and interest and penalties keep accumulating.¹ This is a strong reason to file even when you can’t pay the balance due. Filing starts the clock; not filing leaves you exposed indefinitely.

Undisclosed Listed Transactions

Participate in a “listed transaction” (a tax shelter the IRS has identified as abusive) and fail to disclose it, and the assessment period stays open until at least one year after you or your material advisor turns over the required information. If nobody discloses, the period stays open indefinitely.⁷

Gifts Without Adequate Disclosure

For gift tax, the statute of limitations runs only if a gift is “adequately disclosed” on Form 709. If you make a taxable gift and either don’t file a gift tax return or don’t include enough detail, the IRS can assess gift tax at any time. Adequate disclosure means identifying the parties, describing the property, and explaining the valuation method including any discounts. A qualified appraisal meeting Treasury standards also works.⁸

Events That Pause the Clock

Some events toll the running of the statute, freezing the countdown while they play out.

The most common is a notice of deficiency, sometimes called a 90-day letter. Once the IRS mails it, the assessment clock stops while you have time to petition the Tax Court, and if you do petition, it stays paused until the court issues a final decision, plus another 60 days.⁹ Bankruptcy also suspends the assessment period while the automatic stay blocks IRS action.¹⁰

For collection, the clock pauses when your assets are under a court’s control, and it stops entirely if you leave the country for a continuous period of six months or more.⁹ Service members in combat zones get separate postponements on both assessment and collection.¹⁰ Federally declared disasters can trigger postponements of up to one year for affected taxpayers.

When the IRS Asks You to Extend the Window

If an audit is still open as the three-year or six-year deadline approaches, the IRS will often ask you to sign an extension. The alternative is unappealing for both sides: the IRS would have to issue a rushed deficiency notice on incomplete work, and you’d lose the chance to provide information that might reduce or eliminate the adjustment.

Two forms are used. Form 872 is a fixed-date extension, setting a specific new expiration date. Form 872-A is open-ended, keeping the window open until either you or the IRS sends a termination notice, at which point the period expires 90 days later.¹¹

Either type can be restricted to specific issues, leaving the normal expiration date in place for everything else. Both must be signed before the existing statute expires to be valid.¹² Signing is voluntary. The IRS can’t force you. But refusing when the agency has open questions usually just accelerates a deficiency notice rather than making the issue disappear.

The Collection Clock Is Separate

The audit statute governs how long the IRS has to determine you owe additional tax. A separate 10-year clock governs how long it has to collect once tax has been assessed, through levy, lien, or court action.¹³

After 10 years, the IRS generally must stop pursuing the debt. The period can stretch, though. An installment agreement extends collection to 90 days past whatever extended timeline was agreed to in writing. If the IRS starts a court proceeding before the 10 years run out, the levy period stays open until the resulting judgment is satisfied or becomes unenforceable.¹³

You might survive an audit with no additional assessment, in which case the collection statute never matters. If the audit ends in a balance due, a fresh 10-year countdown begins with its own tolling rules for bankruptcy, court-controlled assets, and time outside the country.

The Refund Clock Runs Out Too

The statute works both ways. Just as the IRS eventually loses the right to assess more tax, you lose the right to claim a refund if you wait too long. The deadline is the later of three years from the date you filed your return or two years from the date you actually paid the tax.¹⁴

File a claim after the three-year window but within the two-year payment window, and your refund is capped at what you paid during those two years. You can’t recover withholding or estimated payments made earlier. Wage withholding and quarterly estimates are treated as paid on the return’s original due date, whatever day the money actually left your paycheck.¹⁵ Miss the deadline and the money is gone. The IRS has no authority to pay a refund once the period expires, even for an obvious overpayment.

How Long to Keep Your Records

Your retention plan should follow the audit windows that apply to you. The IRS’s minimums:¹⁶

Three years for most taxpayers who filed complete and accurate returns.
Six years if you might have unreported income exceeding 25% of the gross income shown on your return.
Seven years if you claimed a deduction for worthless securities or bad debt.
Indefinitely if you never filed, or if you filed a fraudulent return.

Property records need extra attention. Keep documentation of purchase price, improvements, and depreciation until the statute of limitations expires for the year you sell or dispose of the asset. If you received property in a tax-free exchange, keep records for both the old and new property until you finally dispose of the replacement in a taxable transaction.¹⁶

Business owners with employees should keep employment tax records at least four years after filing the fourth-quarter return for the year. Records tied to qualified sick and family leave wages or the employee retention credit must be kept at least six years.¹⁷

1
Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection
2
Internal Revenue Service. IRS Opens 2026 Filing Season
3
Office of the Law Revision Counsel. 26 USC 7502 – Timely Mailing Treated as Timely Filing and Paying
4
Internal Revenue Service. Overview of Statute of Limitations on the Assessment of Tax
5
Internal Revenue Service. IRM 8.11.6 – FBAR Penalties
6
Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty
7
Federal Register. Period of Limitations on Assessment for Listed Transactions Not Disclosed Under Section 6011
8
Internal Revenue Service. Treasury Decision 8845 – Adequate Disclosure of Gifts
9
Office of the Law Revision Counsel. 26 USC 6503 – Suspension of Running of Period of Limitation
10
Internal Revenue Service. IRM 25.6.1 – Statute of Limitations Processes and Procedures
11
Internal Revenue Service. EP Examination Process Guide – Section 7 – Appeals – Statute Protections
12
Internal Revenue Service. IRM 25.6.22 – Statute of Limitations Processes
13
Office of the Law Revision Counsel. 26 USC 6502 – Collection After Assessment
14
Internal Revenue Service. Time You Can Claim a Credit or Refund
15
Office of the Law Revision Counsel. 26 USC 6511 – Limitations on Credit or Refund
16
Internal Revenue Service. How Long Should I Keep Records
17
Internal Revenue Service. Employment Tax Recordkeeping