The IRS can go back three years for most audits, six years if it suspects you underreported income by 25 percent or more, and indefinitely if it believes you committed tax fraud or did not file at all.

The length of time the IRS can examine your past tax returns depends on what they are looking for and what you reported. A standard audit covers the last three years of returns. If the IRS finds that you left off income — not just made a math error, but actually failed to report money you received — the window stretches to six years. If the IRS suspects intentional fraud, there is no time limit at all.

Understanding these timeframes matters because they affect what records you need to keep, what years might be at risk if you made a mistake, and how long you should expect the IRS to have an active interest in your file. The rules also vary slightly depending on whether you are a business owner, whether you filed late, and whether you filed at all.

Key Takeaways

  • The IRS has three years from the date you filed to audit a return for standard issues like deductions or credits.
  • If you underreported your income by 25 percent or more, the IRS can go back six years instead of three.
  • There is no time limit if the IRS believes you committed fraud or if you never filed a return for a given year.
  • You should keep tax records, receipts, and documentation for at least six years to protect yourself if the IRS comes looking.
  • The clock starts from the date you filed your return, not from the tax year itself — filing late can extend the window.

The three-year standard lookback period

For most audits, the IRS operates under a three-year statute of limitations. This means the IRS generally has three years from the date you filed your return to examine it and assess additional tax. If you filed on April 15, the three-year window closes on April 15 three years later.

This three-year window covers typical audit issues: whether you claimed deductions you were not may have access to to, whether you reported all your income correctly, whether you took a credit you did not may have access to for, or whether you made calculation errors. The IRS does not need a reason to audit within this window — they can select returns at random, or based on patterns they notice.

If you filed your return late, the clock still starts from the date you actually filed, not from the tax deadline. If you filed in July instead of April, your three-year window runs from July. This is why filing late can actually extend the period during which the IRS can examine your return.

The six-year window for substantial underreporting of income

If the IRS discovers that you underreported your income by 25 percent or more, the statute of limitations extends to six years. Underreporting means you did not report income you actually received — not that you claimed deductions that turned out to be wrong.

The 25 percent threshold is calculated against the income you actually reported on your return. If you reported $40,000 in income but actually received $60,000, you underreported by $20,000, which is 50 percent of what you reported. That triggers the six-year window. If you reported $40,000 but received $50,000, you underreported by $10,000, which is 25 percent — that also triggers it. If you reported $40,000 but received $49,000, you underreported by $9,000, which is 22.5 percent — that stays within the three-year window.

This rule applies to business owners, self-employed people, and anyone else who receives income that is not automatically reported to the IRS by a third party. W-2 employees are less likely to trigger this rule because their employer reports their wages to the IRS, making underreporting harder to hide.

No time limit for fraud or unfiled returns

If the IRS believes you committed tax fraud — meaning you intentionally and knowingly misrepresented your income or deductions — there is no statute of limitations. The IRS can go back as far as it wants. Fraud is a serious allegation and requires evidence of intent, not just a mistake or even a reckless error.

Similarly, if you never filed a return for a particular tax year, the IRS has no time limit to assess tax for that year. The statute of limitations only starts running once a return is filed. If you owe tax for 2015 and never filed, the IRS can still pursue that debt in 2024 and beyond.

The IRS also has no time limit to collect a tax debt once it has assessed one, though there are rules about how aggressively they can pursue collection and when the debt becomes uncollectible due to age or hardship.

How the filing date affects the clock

The statute of limitations runs from the date you filed your return, not from April 15 of the year after the tax year ended. This distinction matters significantly.

If you filed your 2023 return on April 10, 2024, your three-year window closes on April 10, 2027. If you filed an extension and did not file until September 15, 2024, your window closes on September 15, 2027. If you filed your 2023 return in 2025 because you missed the deadline and the extension, your window does not close until 2028.

Filing early does not shorten the window — it just closes it sooner. Filing late extends it. This is one reason the IRS sometimes prefers that people file late rather than not file at all: at least a late filing starts the clock ticking.

What records you should keep and for how long

Because the IRS can go back six years in many situations, you should keep all tax-related records for at least six years. This includes receipts, invoices, bank statements, cancelled checks, mileage logs, medical records (if you claimed medical deductions), charitable donation receipts, and any other documentation that supports the numbers on your return.

For business owners and self-employed people, the stakes are higher because underreporting income is more common and the six-year window is more likely to apply. Keep records of all income sources, all business expenses, and all deductions you claimed.

You should also keep copies of your actual filed returns — the version you submitted to the IRS, not just a draft. If the IRS audits you, you will need to show what you actually reported, not what you meant to report or what you think you reported.

Statute of limitations for specific situations

Some situations have their own rules. If you claimed a loss carryback or carryforward — a business loss you are applying to other years — the IRS can examine the year you are carrying the loss to as well as the year you generated it. If you amended a return using Form 1040-X, the IRS can examine the amended return within three years of the amendment, even if the original return is outside the normal window.

If you are part of a partnership, S corporation, or other pass-through entity, the statute of limitations for the entity itself may differ from your personal return. The IRS can also examine the entity's return and your personal return in connection with each other.

If you received a notice of deficiency from the IRS, you have specific rights and deadlines to respond. The statute of limitations may be suspended or extended while you are disputing the assessment in Tax Court or while you are negotiating with the IRS.

What happens when the IRS contacts you about old returns

If the IRS sends you a notice about a return from several years ago, check the date you filed that return. If it is outside the normal statute of limitations and you did not underreport income substantially, you may have grounds to challenge the audit based on timing alone.

However, do not assume the IRS made a mistake. The IRS tracks these dates carefully, and they would not contact you if they did not believe they were within their authority. If you believe they are outside the statute of limitations, you can raise that as a defense, but you will need to prove the filing date.

Keep any correspondence from the IRS, including the envelope it came in, because the postmark date can matter. If the IRS is claiming they sent you notice within the statute of limitations but you received it after, the timing of receipt versus mailing can affect your rights.

Frequently Asked Questions

Can the IRS audit a return from 10 years ago?

Only if you never filed a return for that year, if you underreported income by 25 percent or more, or if the IRS suspects fraud. For a standard audit of a filed return, the limit is three years, or six years if substantial income was underreported. If none of those apply, the IRS cannot audit a return from 10 years ago.

Does filing an amended return restart the statute of limitations?

Yes. When you file an amended return using Form 1040-X, the IRS gets a new three-year window from the date you filed the amendment. This is one reason people sometimes hesitate to amend old returns — it can reopen the audit window for that year.

What if I filed my return but the IRS says I did not?

Request a transcript from the IRS showing whether they received your return. You can order transcripts online through IRS.gov or by calling 1-800-908-9946. If you filed but the IRS has no record, you will need proof of filing — a copy of your return with a postmark, a filing confirmation if you filed electronically, or a receipt from a tax professional.

Does the statute of limitations apply to state taxes too?

No. Each state has its own statute of limitations for state income tax audits. Some states follow the federal three-year rule, but others allow four, five, or six years. Check your state's tax authority website for the specific rules in your state.

If I owe back taxes, can the IRS collect them forever?

The IRS can pursue collection for 10 years from the date they assessed the tax, though there are exceptions. After 10 years, the debt is generally uncollectible, though the IRS can still try to collect if you file a return or receive a refund. Bankruptcy, offers in compromise, and payment plans can all affect how the IRS pursues an old debt.