How Long Does the IRS Have to Audit a Return?

By Forrest Baumhover, CFP®, EA · Last verified October 21, 2026

Assessment statute expiration date (ASED) calculator: the last day the IRS can assess more tax on a return.

The assessment statute expiration date (ASED) is the last day the IRS can assess more tax on a return (IRC §6501(a)). This calculator finds it for one income tax return and shows the rule that produced it.

This clock limits adding tax to a return. The CSED Calculator covers the separate clock that limits collecting tax the IRS has already assessed.

What this tool does, and what it does not

It dates these rules for one income tax return, such as a Form 1040:

Three years from the filing date (IRC §6501(a)). A return the IRS receives early counts as filed on April 15, the last day the law prescribes, without regard to any extension (IRC §6501(b)(1); 26 CFR §301.6501(b)-1(a)).
Six years when the return omits more than 25 percent of the gross income it states, or more than $5,000 of income from a foreign asset that section 6038D covers, even below its reporting threshold (IRC §6501(e)(1)(A)).
No limit when the taxpayer filed no return, or filed a false or fraudulent one to evade tax (IRC §6501(c)(1), (3)). The tool returns no ASED.
A Form 872 extension that both sides signed before the period ended (IRC §6501(c)(4)(A)).
A notice of deficiency: the 90-day petition period (150 days if the notice went to a person outside the United States), or until a Tax Court decision becomes final, plus 60 days (IRC §6503(a)(1); IRC §6213(a)).
An amended return the IRS receives in the last 60 days of the period (IRC §6501(c)(7)).
A last day on a Saturday, Sunday or D.C. legal holiday moves to the next business day (IRC §7503; 26 CFR §301.7503-1).

When you check an event the tool cannot date, such as a bankruptcy (IRC §6503(h)(1)) or an offer in compromise (IRM 5.8.10.8), it gives no ASED. It shows the date before that event as a floor.

How to use it

Enter the tax year and the date the IRS received the return. A return received on or before April 15 of the next year counts as filed April 15. A later return counts when received, including one received during an extension or a disaster postponement (IRM 25.6.1.9.3; IRM 25.6.1.6.15).
Enter the postmark date instead when the timely mailing rule applies: a return postmarked by April 15 counts as filed April 15, and one postmarked by an extended due date counts as filed on the postmark date when it arrives after that date (IRM 25.6.1.6.15).

For the six-year test, leave out any item the return disclosed adequately, except an overstatement of basis, which counts even when disclosed. Gross income for a trade or business means receipts before the cost of sales or services (IRC §6501(e)(1)(B)).

The rule behind it

Count from the date the taxpayer filed the return, never from the date the taxpayer signed it (IRC §6501(a)). The IRS received date does not necessarily establish the filing date, so apply the filing rules first (IRM 25.6.1.9.3).

The early-return rule starts the three years on April 15 even when April 15 falls on a weekend, because IRC §7503 does not move an early return's filing date (IRM 25.6.1.6.15).

A notice of deficiency suspends the period from the day after the IRS mails it, not the day the taxpayer receives it (IRM 25.6.1.9.6.2). The six-year rule reaches every item on the return, not just the omitted items (IRM 25.6.1.9.5.3).

The source pages show these dates: IRM 25.6.1.6.15 (10-25-2024), 25.6.1.9.3 (03-01-2006), 25.6.1.9.5.3 (10-01-2026), 25.6.1.9.6.2 (09-29-2015), 25.6.22.3 (03-26-2019), 25.6.22.8 (08-26-2011).

Worked example

A client files the 2023 return on March 1, 2024. The filing date becomes April 15, 2024, and the ASED is April 15, 2027, a Thursday.

When the ASED is near

Expect a Form 872 request when an examination is open near the ASED. Each time, the IRS must tell the taxpayer the right to refuse the extension or to limit it to particular issues or a period (IRC §6501(c)(4)(B); IRM 25.6.22.3).

A client who signs gives the IRS more time to assess every issue the form covers. A restricted consent covers only the issues it names, and the statute expires on all others (IRM 25.6.22.8). The IRS discourages restricted consents until the examination has identified every issue, and as a general rule grants one only when the conditions in IRM 25.6.22.8.2 hold, so treat it as a request, not a right (IRM 25.6.22.8.1).

If a client refuses, the IRS may issue a notice of deficiency or take other appropriate action (IRM 25.6.22.3). A Form 872-A has no fixed date, which is why this tool cannot date it (IRM 25.6.22.5.7).

When to call a practitioner

You checked an event the tool cannot date, or a Tax Court petition is pending.
An account transcript shows a TC 560, which the IRS enters to update the ASED (IRM 25.6.1.9.5.3).
The tool and the IRS disagree, or the date is within weeks of today.

Common Questions

How long does the IRS have to audit a return?

Generally three years from the date the return counts as filed, and a return filed before April 15 counts as filed April 15 (IRC §6501(a), (b)(1)). The limit applies to assessing more tax. It runs six years for a substantial omission and has no end when the taxpayer filed no return or filed a fraudulent one (IRC §6501(e)(1), (c)(1), (3)).

What is the assessment statute expiration date?

It is the ASED, the last day the IRS can assess more tax on a return. The IRS records it on the taxpayer's account (IRM 25.6.1.9.5.3).

When does the IRS 6-year statute of limitations apply?

When the return omits more than 25 percent of the gross income it states, or more than $5,000 of income from a foreign asset that section 6038D covers, even below its reporting threshold (IRC §6501(e)(1)(A)). An item the return disclosed adequately does not count as omitted, but an overstatement of basis counts even when disclosed (IRC §6501(e)(1)(B)(ii), (iii)).

Does an amended return extend the statute of limitations?

Usually not (IRM 25.6.1.9.4.2). The exception: a signed document showing more tax that the IRS receives in the last 60 days keeps the period open for that tax until 60 days after receipt (IRC §6501(c)(7)).

What happens if the taxpayer refuses to sign a Form 872?

The IRS may issue a notice of deficiency or take other appropriate action (IRM 25.6.22.3). The notice suspends the statute during the petition period, or until a Tax Court decision becomes final if the taxpayer petitions, plus 60 days (IRC §6503(a)(1); IRC §6213(a)).

Does filing on extension change the ASED?

Yes. A return the IRS receives during an extension counts as filed when received, so the three years start on that date, not on April 15 (IRM 25.6.1.9.3).

More from the Desk

More practitioner writing from Forrest Baumhover, CFP®, EA at The Federal Tax Desk on Substack.

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Sources

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