Explains what the IRS asks for when it reviews a filed tax return, how long supporting records must be kept, and the deadlines for responding to or appealing the examination findings, for individual and business taxpayers notified that their return is under audit.
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| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/businesses/small-businesses-self-employed/irs-audits |
| General statute of limitations for assessment | a time period established by law when IRS can review, analyze, and resolve your tax-related issues; it is generally three years after a return is due or was filed, whichever is later | applies unless extended or another period applies |
| Extension to respond to a mail audit | a one-time automatic 30-day extension | requested by fax or mail to the number/address on the IRS letter |
| Extension after a Notice of Deficiency | not available once a "Notice of Deficiency" is received by certified mail; the time to petition the U.S. Tax Court cannot be extended beyond the original 90 days |
This Guide covers the Internal Revenue Service's examination (audit) process: how a taxpayer is notified, what supporting documents the IRS asks for, how long those records must be kept, and the deadlines for agreeing with or disputing the examination findings. Figures are for tax year 2026.
This is for individual and business taxpayers who have been notified that a filed federal income tax return has been selected for examination. The IRS conducts audits either by mail or through an in-person interview to review your records, and the interview may be at an IRS office (office audit) or at the taxpayer's home, place of business, or accountant's/representative's office (field audit).
Should your account be selected for audit, the IRS will notify you by mail, and it won't initiate an audit by telephone. It does not apply to state tax audits, to criminal tax investigations, or to a case already before the U.S. Tax Court.
Statute of limitations and response deadlines
| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/businesses/small-businesses-self-employed/irs-audits |
| General statute of limitations for assessment | a time period established by law when IRS can review, analyze, and resolve your tax-related issues; it is generally three years after a return is due or was filed, whichever is later | applies unless extended or another period applies |
| Extension to respond to a mail audit | a one-time automatic 30-day extension | requested by fax or mail to the number/address on the IRS letter |
| Extension after a Notice of Deficiency | not available once a "Notice of Deficiency" is received by certified mail; the time to petition the U.S. Tax Court cannot be extended beyond the original 90 days |
Assessment statute detail
| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/filing/time-irs-can-assess-tax |
| General assessment period (ASED) | within 3 years after your return was due, including extensions, or – if you filed late – within 3 years after the IRS received your return, whichever is later; this is called the Assessment Statute Expiration Date | |
| Substantial understatement of income | where you reported 25% or less of your income on your tax return, the time the IRS can assess additional tax increases from 3 to 6 years from the date you filed your tax return | |
| False or fraudulent return | filed a false or fraudulent return with intent to avoid tax; the IRS can assess tax for an unlimited amount of time | |
| Notice of deficiency (90-day letter) response window | once issued, you have 90 days (150 days if you live outside the United States) to agree with the proposed assessment or to file a petition with the Tax Court before the IRS can assess the amount due |
Record retention periods
| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/businesses/small-businesses-self-employed/how-long-should-i-keep-records |
| General records | 3 years if situations (4), (5), and (6) below do not apply to you | |
| Claim for credit or refund filed after the return | 3 years from the date you filed your original return or 2 years from the date you paid the tax, whichever is later | |
| Loss from worthless securities or bad debt deduction | 7 years | |
| Fraudulent return filed | keep records indefinitely | |
| Employment tax records | at least 4 years after the date that the tax becomes due or is paid, whichever is later | same period stated at https://www.irs.gov/taxtopics/tc305 |
| Property records | until the period of limitations expires for the year in which you dispose of the property | needed to figure depreciation, amortization, depletion, gain or loss |
Disputing the findings
| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/appeals/preparing-a-request-for-appeals |
| Deadline to file a formal written protest | within the time limit specified in the letter that offers you the right to appeal the proposed changes; generally the time limit is 30 days from the date of the letter | |
| Small Case Request eligibility threshold | the entire amount of additional tax and penalty proposed for each tax period is $25,000 or less from an examination (audit) | employee plans, exempt organizations, S corporations and partnerships are not eligible for Small Case Requests |
Audit reconsideration
| What | Value | Note |
|---|---|---|
| Source | all figures below | https://www.irs.gov/credits-deductions/audit-reconsideration-process-for-correspondence-examination-audits-by-mail |
| Estimated IRS response time to a reconsideration request | a 30-day response time, but it may take longer, potentially several months | can check status online or call the number on the letter |
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