IRS Deadlines to Audit, Assess, and Collect Tax
The three-year, six-year, and unlimited assessment periods, the ten-year collection deadline and what pauses it, and the refund claim window.
Reviewed by the Fairlight Accounting cross-border tax team — U.S. & Canadian Tax Desks
The IRS generally has three years from filing to assess additional tax, six years for omissions over 25 percent of gross income or $5,000 of income from foreign financial assets, and no limit for unfiled or fraudulent returns. It then has ten years to collect assessed tax, with pauses for pending payment plan requests, offers, hearings, and bankruptcy.
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What are the assessment periods?
| Situation | Period |
|---|---|
| Ordinary return | 3 years from the later of filing or the due date |
| Omitted more than 25% of gross income | 6 years |
| Omitted more than $5,000 of income from specified foreign financial assets | 6 years |
| Required foreign information form (such as Forms 5471, 3520, 8938) not filed | Period stays open for the whole return until 3 years after the form is filed (only the related items if the failure had reasonable cause) |
| Fraudulent return | No limit |
| No return filed | No limit |
| Return filed early | Treated as filed on the due date |
The IRS can ask you to extend the period on Form 872 when an audit is running late. You can agree, limit the extension to specific issues, or decline — in which case the IRS usually issues a notice of deficiency to protect the period.
How long can the IRS collect?
Ten years from the date of assessment, called the collection statute expiration date. When it passes, the remaining balance is written off. Several events pause the clock, extending the deadline by the time they were pending plus, in some cases, an added period:
- a pending installment agreement request, and 30 days after rejection or termination, plus any appeal of that decision
- a pending offer in compromise, plus 30 days after rejection and any appeal
- a timely requested collection due process hearing
- bankruptcy, plus six months
- living outside the United States for a continuous period of at least six months
- innocent spouse requests, for the requesting spouse, plus 60 days
How long do you have to claim a refund?
A refund claim must be filed within three years of filing the return or two years of paying the tax, whichever is later, and the refund is limited to tax paid in that window. A late original return counts as the claim, but withholding and estimated payments are treated as paid on the original due date, so a return filed more than three years after that date (plus any extension) generally loses the refund.
Frequently asked questions
Does an amended return restart the three years?
Generally no, except that an amended return filed within 60 days of the deadline showing additional tax gives the IRS 60 days to assess that tax.
Does the six-year rule apply if the omission was an honest mistake?
Yes. The six-year period depends on the size of the omission, not intent. An amount disclosed on the return in a way that alerts the IRS to its nature is not treated as omitted.
Can the IRS collect after ten years if I signed a waiver?
Only in narrow cases. Since 2000, the IRS can extend the collection period by written agreement only when it grants an installment agreement (the extension then ends 90 days after the agreed period) or releases a levy after the ten years have run.
How do I find my collection deadline?
Request your account transcript; the assessment dates appear there. Tolling events must be added manually or by requesting the IRS's computed date.
Official sources
The IRS explains: “The period of limitations is the period of time in which you can amend your tax return to claim a credit or refund, or the IRS can assess additional tax.” — Internal Revenue Service, How long should I keep records?, https://www.irs.gov/businesses/small-businesses-self-employed/how-long-should-i-keep-records
The Internal Revenue Manual explains: “Internal Revenue Code (IRC) 6502 provides that the length of the period for collection after assessment of a tax liability is 10 years. The collection statute expiration ends the government's right to pursue collection of a liability.” — Internal Revenue Service, 5.1.19 Collection Statute Expiration, https://www.irs.gov/irm/part5/irm_05-001-019
Next step
Fairlight Accounting handles U.S. domestic, cross-border (U.S.–Canada), and international tax returns, plus bookkeeping, payroll, and CFO advisory. Our U.S. Tax Desk reads account transcripts to establish which years are open and when a balance expires. See pricing or book a free fit call.
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