IRS Audit Statute of Limitations: How Long the IRS Can Audit You

Understanding the IRS Audit Statute of Limitations helps you see how long the IRS can review your past tax returns and assess additional tax. Most IRS examinations occur within the standard three-year window. However, recent enforcement data shows that the IRS continues to review returns beyond that period, especially for higher-income filings.

For tax year 2019, 11% of taxpayers with a total positive income of $10 million or more were audited. The rate reached 3.1% for those earning $5 million to $10 million and 1.6% for those earning $1 million to $5 million. In fiscal year 2024, the IRS closed more than 505,000 audits, generating over $29 billion in recommended additional tax, along with 1.2 million automated underreporter cases and 442,633 substitute-for-return cases.

With this level of scrutiny, it’s natural to want a clear understanding of how far back the IRS can look and when your tax years finally close.

What the IRS Audit Statute of Limitations Means

The IRS uses a statute of limitations to limit how long it can audit your tax return and assess additional tax. Once that window closes, the IRS can’t reopen that year unless a specific exception applies. The timeline depends on your filing date, the type of income you report, and whether the IRS identifies major issues.

For most people, the window stays open for three years. However, certain situations extend that window to six years or remove the limit entirely. This is where many taxpayers get confused, especially expats and business owners with multiple forms, foreign income, or late filings.

How Long the IRS Has to Audit You Under the Three-Year Rule

The standard IRS audit period is 3 years. The IRS starts counting from the later of:

• The tax return’s original due date
• The date you filed the return

Note that filing early doesn’t shorten the window. For example, suppose you filed your 2023 return on March 10, 2024. The three-year clock begins on April 15, 2024, not when you filed early.

Filing late, on the other hand, changes the timeline. When you file your return after the due date, the statute starts on the date you actually filed. So if you file on November 1, the IRS will have until November 1 three years later.

When the IRS Can Look Back Six Years

Certain situations extend the window to six years. The most common trigger involves a large understatement of income.

1. You Underreported Your Income by More Than 25%

The IRS may extend the audit period to six years when it finds you left out more than 25% of your gross income. This includes income from work, investments, gig work, rentals, or certain foreign accounts.

For example:

You reported $100,000 in income. The IRS later discovers $30,000 in additional income. Because the omitted income exceeds 25%, the IRS now has six years to audit that return.

2. You Fail More Than $5,000 of Foreign Income

You also trigger the six-year period when you omit more than $5,000 of foreign income. This applies to interest, dividends, wages, or other foreign-source income. The IRS takes unreported foreign income seriously, even if the omission was unintentional.

When the IRS Has No Audit Deadline at All

Some actions remove the time limits entirely. In these cases, the IRS can audit at any point in the future.

The unlimited period applies when:

• You never filed a tax return
• You filed a false or fraudulent return
• You intentionally tried to evade tax
• You forgot to sign your return (treated as unfiled)
• You failed to file certain international forms, such as Form 5471 for foreign corporations

Missing international forms can keep the entire tax return open indefinitely, even when the income itself wasn’t large. This rule catches expats and business owners who weren’t aware of additional reporting obligations.

Can the IRS Extend the Statute of Limitations?

The IRS may ask you to extend the statute of limitations by having you sign a consent form. This usually happens near the end of the normal audit window when an examination remains unresolved.

Why the IRS Requests an Extension

Common reasons include:

• The IRS needs more time to review complex items
• You filed an appeal and need more time to resolve it
• The IRS wants to complete a case without issuing a rushed assessment

Consent agreements can be fixed-date or open-ended, depending on the situation.

Should You Agree to Extend the Deadline?

Extensions help when you’re negotiating, requesting appeals, or waiting on documents. However, when the extension only benefits the IRS, declining may make sense. You should weigh the risks before signing anything.

How IRS Audit Timelines Work

You’ll often hear taxpayers say most audits happen within two years. That’s generally true. The IRS follows an internal guideline called the examination cycle, which instructs agents to open and close audits within about 26 months.

Key points:

• Refund-related audits start quickly
• Office and correspondence audits often start within a year
• Large or complex audits take longer
• High-income returns and business returns attract more attention

When two full years pass without any IRS contact, the odds of an audit drop sharply for most taxpayers unless an exception applies.

Which Audit Triggers Extend How Far Back the IRS Can Look

Audit selections follow IRS scoring systems and patterns. Certain entries on your return can prompt deeper review and even push the IRS to examine older years.

Frequent Triggers Include:

• Large deductions compared with income
• Consistent business losses
• High charitable contributions
• Omitted income from wages or gigs
• Cash-heavy businesses
• Foreign income reporting issues
• Large changes from year to year

The IRS uses data matching to compare your return with reports from employers, banks, and third parties. When something doesn’t match, the IRS may look back multiple years to understand the pattern.

How Long You Should Keep Your Tax Records

Recordkeeping supports your position when the IRS questions an item from a past return. At a minimum:

• Three years for most taxpayers
• Six years if your return includes foreign income or if income could’ve been understated
• Indefinitely for unfiled returns, fraud investigations, or years with missing international forms

You’ll want to organize documents by category: income, business expenses, home-office records, charitable contributions, and foreign account statements. A simple folder system prevents delays if an audit ever arises.

What Happens When the IRS Audits an Older Tax Year?

When the IRS reviews a year beyond the three-year limit, the process looks similar to a standard audit. You’ll receive a notice requesting specific documents or explanations.

You may need to provide:

• Bank statements
• Income records
• Proof of deductions
• Foreign account documents
• Business records
• Statements from previous tax preparers, if applicable

A correspondence audit usually handles simple issues by mail. More complex cases, including high-income returns or business activity, may require an in-person meeting or a review at your location.

IRS Audit Timeline Examples

Example 1: Standard Three-Year Window

• Filed 2022 return on April 15, 2023. 
• IRS deadline to audit ends April 15, 2026.

Example 2: Filing Late

• Filed 2021 return on November 10, 2023.
• IRS deadline to audit ends November 10, 2026.

Example 3: Substantial Underreporting

• Missed $30,000 in foreign contractor income.
• IRS can audit the last six years.

Example 4: Missing Form 5471

• You own 25% of a foreign corporation but never filed Form 5471.
• Entire return remains open indefinitely.

Example 5: No Tax Return Filed

• Didn’t file 2016–2020 returns due to working overseas.
• IRS may audit all years because the statute never began.

Frequently Asked Questions

How far back can the IRS audit you?

The IRS usually reviews the past three years, but certain issues allow a longer lookback period. Underreported income or foreign income over $5,000 can extend the audit window to six years. Fraud, missing forms, or unfiled returns remove the deadline completely.

Does the statute of limitations apply when you never filed a return?

The statute only applies once a tax return has been filed. When no return exists, the IRS can review that year at any time. This means the IRS may assess tax, penalties, and interest with no expiration date.

Does filing an amended return start a new deadline?

Filing an amended return doesn’t reset the original statute of limitations. The IRS still follows the same deadline unless the amended return reveals major changes. In those cases, the IRS may review the return more closely but within the same timeframe.

Can the IRS reopen a closed tax year?

The IRS generally cannot reopen a year once the statute expires. However, the agency can revisit any year with fraud, non-filing, or missing required forms. When these issues appear, the IRS gains the authority to reassess that year without time limits.

How long does an IRS audit normally take?

Most audits conclude within several months, especially correspondence audits handled by mail. More complex audits involving businesses or foreign income can run longer. The timeline depends on how quickly you provide documents and how complex the issues are.

Take the Next Step With Confidence

The statute of limitations protects you from open-ended scrutiny. That limit gives you certainty, helps you plan, and tells you exactly how long you need to keep old records. It also forces the IRS to act within a reasonable timeframe, so you’re not dealing with issues long after the fact.

Understanding that timeline helps you focus on your current goals instead of worrying about what might resurface from the past. You deserve a clear picture of where you stand and what, if anything, still needs attention.

If you want help reviewing past filings, addressing open risks, or preparing for an audit, our team can guide you each step of the way. Request a consultation today and move forward with confidence.