How far back can the IRS go: the statute of limitations

Knowing how long the IRS can look back tells you how long to keep records, when old years become safe, and why unfiled returns are so risky. This guide sets out the main time limits.

By Mirza Fahad Baig, Chartered Accountant. Reviewed by Hamza Fida, Chartered Accountant. Checked against official sources on . 2 minute read.

Short answer

The IRS statute of limitations generally gives the IRS three years from filing, or the due date if later, to assess more tax. It is six years if income was understated by more than 25%, with no limit for unfiled or fraudulent returns. Missing international forms such as Form 5472 keeps the return open. Assessed tax can be collected for ten years.

At a glance

Normal assessment period
3 years from filing
Large omission of income
6 years
No return or fraud
No time limit
Missing international forms
Return stays open until filed
Collection
10 years from assessment
Refund claims
3 years from filing or 2 from payment
How far back can the IRS go: the statute of limitationsNormal assessment period: 3 years from filing; Large omission of income: 6 years; No return or fraud: No time limit; Missing international forms: Return stays open until filed; Collection: 10 years from assessment; Refund claims: 3 years from filing or 2 from payment.KEY FACTS AT A GLANCEHow far back can the IRS go: the statute oflimitationsNormal assessment period3 years from filingLarge omission of income6 yearsNo return or fraudNo time limitMissing international formsReturn stays open untilfiledCollection10 years from assessmentRefund claims3 years from filing or 2from paymentChecked against official sourcesTax BakersHow far back can the IRS go: the statute of limitationsNormal assessment period: 3 years from filing; Large omission of income: 6 years; No return or fraud: No time limit; Missing international forms: Return stays open until filed; Collection: 10 years from assessment; Refund claims: 3 years from filing or 2 from payment.KEY FACTS AT A GLANCEHow far back can the IRS go: thestatute of limitationsNormal assessment period3 years from filingLarge omission of income6 yearsNo return or fraudNo time limitMissing international formsReturn stays open until filedCollection10 years from assessmentRefund claims3 years from filing or 2 from paymentChecked against official sourcesTax Bakers
Key facts at a glance, as set out in this guide.

What are the main time limits?

SituationTime limit
Normal assessment of additional tax3 years from the later of filing or the due date
Income understated by more than 25% of what was reported6 years
No return filedNo limit
Fraudulent returnNo limit
Required international information return not filed, such as Form 5472, 3520 or 8938Assessment period does not start until it is filed
Collecting tax already assessed10 years from assessment
Claiming a refund3 years from filing or 2 years from payment, whichever is later

Why are unfiled returns so risky?

Because the clock never starts. A business that did not file for a year can be assessed for that year at any time, with penalties and interest from the original due date. Filing, even late, starts the three-year period running. See if your LLC never filed and filing back taxes.

How do international forms affect it?

If a required international information return, such as Form 5472 for a foreign-owned LLC, is not filed, the assessment period for the whole tax return generally stays open until the form is filed, and for three years after. This makes missing Form 5472 more serious than it first appears. See Form 5472 and FBAR vs Form 8938.

What does this mean for records?

  1. Keep most records for at least three years

    From the date the return was filed.

  2. Keep them six years if income could be questioned

    Or if you are unsure.

  3. Keep asset records longer

    For as long as you own the asset plus the period after sale.

  4. Keep employment tax records four years

    After the tax was due or paid.

See how long to keep business records.

Can the period be extended?

Yes. During an audit the IRS may ask you to sign an agreement extending the assessment period. You can refuse or limit it to certain issues, but refusing often leads the IRS to assess based on the information it has. The ten-year collection period can also be suspended, for example during bankruptcy or while an offer in compromise is pending.

Do states follow the same limits?

Many use similar periods, but some are longer, and states often have extra time after a federal change is reported. Check each state where you file. See how states tax LLCs.

Worried about past years?

We check which years are still open, file what is missing, and help you close old periods so the clock starts running.

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Questions people ask

How far back can the IRS audit?

Usually three years from filing, six years for income understated by more than 25%, and without limit for unfiled or fraudulent returns.

How long can the IRS collect a tax debt?

Generally ten years from the date the tax was assessed.

Does not filing Form 5472 affect the statute of limitations?

Yes. The assessment period for the related return generally stays open until the form is filed.

How long do I have to claim a tax refund?

Three years from filing or two years from payment, whichever is later.

Sources

Every fee, date and rule on this page was taken from these official and primary sources.

  1. IRS: Time IRS can assess tax
  2. IRS: Time IRS can collect tax
  3. Internal Revenue Code section 6501: limitations on assessment and collection

Rules and fees change. If you are reading this long after October 1, 2026, confirm the figures with the source before you rely on them.

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This guide is general information. It is not tax or legal advice for your situation.