# IRS audit statute of limitations: how far back the IRS can go

Source: https://backtaxesdesk.com/irs-audits/irs-audit-statute-of-limitations
Publisher: Back Taxes Desk (backtaxesdesk.com), independent editorial site
Topic: Audits and Appeals
Last updated: 2026-09-19

> The IRS audit statute of limitations is generally three years from the date a return was filed, under Internal Revenue Code section 6501. It becomes six years if you left out more than 25% of the gross income shown on the return, and there is no limit for a fraudulent return or a year with no return filed.

## Key facts

- General assessment limit: 3 years after the return was filed (IRC 6501(a))
- Early returns: Treated as filed on the due date
- Substantial omission: 6 years if omitted income exceeds 25% of reported gross income
- Fraud or no return: No time limit
- Bad debt or worthless securities records: Keep 7 years
- IRS practice: Usually no more than the last 6 years

## How far back can the IRS audit?

The IRS can generally assess extra tax for three years after a return was filed, which is why the IRS says audits usually include returns filed within the last three years. The rule is in Internal Revenue Code section 6501(a). The IRS adds that when it finds a substantial error it may reach further, but it usually does not go back more than six years ([IRS, IRS audits](https://www.irs.gov/businesses/small-businesses-self-employed/irs-audits)).

The IRS audit statute of limitations is a deadline on **assessment**, the formal recording of tax you owe. An audit has to be finished, and any extra tax assessed, before that date. The clock is sometimes called the assessment statute expiration date, or ASED.

## When does the IRS 3 year statute of limitations start?

The three years run from the date you filed, not from the end of the tax year. If you file early, section 6501(b)(1) treats the return as filed on its due date, so filing in February does not start the clock sooner than the April deadline.

### Worked dates

| Tax year | Return filed | Treated as filed | Assessment period normally ends |
| --- | --- | --- | --- |
| 2023 | February 20, 2024 | April 15, 2024 | April 15, 2027 |
| 2023 | October 15, 2024 (on extension) | October 15, 2024 | October 15, 2027 |
| 2025 | March 2, 2026 | April 15, 2026 | April 15, 2029 |
| 2026 | Due April 15, 2027 | Date filed, if on or after the due date | Three years after filing |

When the 3-year window closes for sample filing dates

A late return starts its own three-year clock on the day the IRS receives it. That is one reason catching up on missing years matters: until a return is filed, the clock for that year does not start at all.

## When the six-year rule applies

The window stretches to six years after filing when you leave out income that is more than 25% of the gross income stated on the return, under section 6501(e)(1)(A). The same six years applies if you omit more than $5,000 of income from certain foreign financial assets.

Example: a return reports $80,000 of gross income. Twenty-five percent of that is $20,000. If $22,000 of consulting income was left off, the omission exceeds the threshold and the IRS has six years to assess. If $15,000 was left off, the ordinary three-year limit still applies, though the IRS can still correct it within those three years.

> **Foreign information returns:** If a required foreign information return is not filed, section 6501(c)(8) keeps the period open until three years after the IRS receives that information.

## Is there a limit if I never filed or the return was fraudulent?

No. Section 6501(c) lets the IRS assess tax at any time for a false or fraudulent return filed with intent to evade tax, for a willful attempt to evade tax, and for any year in which no return was filed. There is no deadline in those cases.

For unfiled years, the IRS usually asks people to file the last six years to be back in good standing, a practice explained on our page about the [unfiled tax returns statute of limitations](https://backtaxesdesk.com/unfiled-returns/unfiled-tax-returns-statute-of-limitations). Filing a return, even years late, starts the ordinary three-year clock for that year.

## Can the IRS extend the audit deadline?

Only with your written agreement. Section 6501(c)(4) lets you and the IRS agree in writing, before the period ends, to keep the year open longer. The IRS normally uses Form 872, Consent to Extend the Time to Assess Tax, for this. You can refuse, but the IRS will then usually close the audit on the information it has and issue a notice of deficiency.

Extensions often come up when an audit runs long or a case goes to Appeals. IRS Publication 5 says an exam case generally needs more than 365 days left on the statute before Appeals will accept it, so you may be asked to sign an extension if you want an [administrative appeal](https://backtaxesdesk.com/irs-audits/irs-appeals-process). Consenting to a limited extension that covers only the disputed issues is sometimes possible, and a representative can ask for it.

## How long should I keep tax records? (The IRS 7 year statute of limitations)

Keep records for as long as the year can be examined. The IRS guidance on [how long to keep records](https://www.irs.gov/businesses/small-businesses-self-employed/how-long-should-i-keep-records) sets these periods. The often-quoted seven-year rule applies only to one situation: a deduction for a bad debt or worthless securities.

Records for property, such as a home, rental or stock, must be kept until the limitations period ends for the year you sell or dispose of it, because they prove your basis. For a house bought in 2010 and sold in 2026, that means keeping purchase and improvement records until at least 2030.

## Audit limits versus the collection and refund clocks

Three separate clocks are often confused. The assessment limit covered here controls how long the IRS can add tax. Once tax is assessed, a separate 10-year period to collect it begins, explained on our [IRS collection statute of limitations](https://backtaxesdesk.com/irs-collections/irs-collection-statute-of-limitations) page. Your own window to claim a refund is generally three years from filing or two years from paying, whichever is later.

Most audits are mail audits that happen well inside the three-year window. See our [correspondence audit](https://backtaxesdesk.com/irs-audits/irs-correspondence-audit) guide for how those work, and the [IRS audit guide](https://backtaxesdesk.com/irs-audits) for the full process.

## Common questions

### Can the IRS audit after 3 years?

Yes, in specific cases. The IRS has six years if more than 25% of gross income was omitted, unlimited time for fraud or unfiled years, and longer if you signed a written extension. Otherwise, assessment is generally barred after three years.

### How many years does the IRS audit at once?

The IRS generally includes returns filed within the last three years. If it finds a substantial error, it may add earlier years, but it says it usually does not go back more than six years.

### Does the IRS 3-year rule start from the tax year or the filing date?

From the filing date. A return filed before the April due date is treated as filed on the due date, and a late return starts its three years when the IRS receives it.

### Should I sign Form 872 to extend the statute?

It depends on the case. Refusing usually leads the IRS to issue a notice of deficiency based on what it has. Signing gives more time to resolve the audit or reach Appeals, and it can sometimes be limited to specific issues.

### Can I throw away tax records after 7 years?

For most people, records can go after three years, except property basis records, records for years with a large omission, and bad debt or worthless securities records. Keep your copies of the returns themselves indefinitely.

## Sources

- [IRS audits](https://www.irs.gov/businesses/small-businesses-self-employed/irs-audits)
- [26 U.S. Code 6501, Limitations on assessment and collection](https://www.law.cornell.edu/uscode/text/26/6501)
- [How long should I keep records?](https://www.irs.gov/businesses/small-businesses-self-employed/how-long-should-i-keep-records)
- [Publication 5, Your Appeal Rights and How to Prepare a Protest](https://www.irs.gov/pub/irs-pdf/p5.pdf)
- [Time IRS can collect tax](https://www.irs.gov/filing/time-irs-can-collect-tax)