Short answer
An IRS audit is a review of a filed return to check that income, deductions and credits are correct. Most audits are handled by mail and ask for specific records. Read the letter for the tax year, the items under review and the response date, then answer by that date. Missing the later 30-day and 90-day deadlines limits your options.
Key takeaways
- Most audits are correspondence audits handled by mail. Office and field audits are interviews with an IRS examiner.
- A CP2000 notice is not an audit. It is an automated income-matching proposal, and it has its own response steps.
- After an exam, a 30-day letter lets you agree or ask the IRS Independent Office of Appeals to review the findings.
- A notice of deficiency gives you 90 days (150 days if addressed to you outside the United States) to petition the U.S. Tax Court, and that deadline cannot be extended.
- Any tax that results is a balance due like any other: payment plans, offers and penalty relief still apply.
How to use this guide
The guide follows the order an audit happens in. First, identify what kind of review you have and what the letter asks for. Then respond, agree or appeal. Then deal with any balance that results. Every page cites the IRS rule or statute behind it.
- Identify the letter. Find the letter or notice number, the tax year and the items listed. Use the table below.
- Check the date. Each audit letter has a response date. The 30-day letter and the notice of deficiency have the deadlines that matter most.
- Gather records. Answer only what the letter asks, with copies, not originals.
- Decide how to respond. Many mail audits can be answered on your own. Field audits, missing records and large amounts are where representation helps most.
Find your audit letter
Know the letter number? Type it into the IRS letter finder to see what it means and where to read next.
The IRS sends audit-related letters in a rough order. The further down this table your letter sits, the closer you are to a hard deadline.
| Stage | Letters and forms | What it means | Read next |
|---|---|---|---|
| Not an audit | CP2000, CP2501 | Income reported to the IRS does not match your return. You can agree or explain. | How to dispute an IRS balance |
| Audit starts | Letter 566, Letter 2205, Form 4564 (records request) | The IRS has opened an exam and wants records or a meeting. | First 10 days after an audit letter |
| Findings proposed | Letter 525, 915 or 950, Form 4549, Form 886-A | The examiner proposes changes. You can agree, partly agree or appeal. | The 30-day letter |
| Hard deadline | Letter 3219, CP3219A | Notice of deficiency. The Tax Court petition clock is running. | Your Tax Court deadline |
| Tax assessed | CP14 and the collection notices that follow | The audit result is now a balance due. | Can’t pay the result |
See audit letters explained for every letter in detail. Not sure a letter is real? Read how to spot a fake IRS letter and compare it with your IRS Online Account.
Each audit letter and form has its own page:
- Letter 566Mail audit has started
- Letter 2205-AField audit contact
- Letter 3572Office audit contact
- Letter 2202Office audit appointment
- Form 4564Information Document Request
- Letter 52530-day letter, mail audits
- Letter 915Office audit report
- Letter 95030-day letter, field audits
- Form 4549Your audit report
- Form 886-AExplanation of items
- Form 870Waiver of restrictions
- Form 872Consent to extend the statute
Audit basics
The IRS generally has three years after a return is filed to assess more tax. That period is six years when more than 25 percent of gross income was left off, and there is no time limit for a fraudulent return or a return that was never filed. The IRS chooses returns through random statistical samples, by comparing returns against norms for similar returns, and through related examinations of business partners or investors. Being selected does not by itself mean the IRS suspects a problem.
- Types of IRS auditsMail, office and field audits
- Audit letters explainedLetter 566, 525, 950, 3219 and Form 4549
- First steps after an audit letterWhat to do in the first 10 days
- How long an audit takesTimelines and the statute of limitations
- What triggers an auditCommon reasons returns are selected
- How far back the IRS can goThree-year, six-year and unlimited periods
- What happens during an auditThe exam step by step
Audits by issue
Most audits look at a few items on the return. These guides cover what the IRS checks for each common item and the records that answer it. See all audit issues.
- Home officeRegular and exclusive use
- Vehicle expensesMileage logs and commuting
- Travel and mealsBusiness purpose and the meal limit
- Hobby lossBusiness or hobby?
- Cash businessHow the IRS tests income
- Rental propertyPassive losses and personal use
- Crypto and digital assetsSales and cost basis
- Amended returnWhen an amendment gets examined
- Deceased taxpayerExecutors and estates
- Charitable deductionsAcknowledgments and appraisals
Respond, agree or appeal
At the end of an exam you can agree with the proposed changes, agree with part of them, or ask for an independent review by the IRS Independent Office of Appeals. If you do nothing, the IRS issues a notice of deficiency, and the U.S. Tax Court becomes the place to dispute the tax before paying it.
| Route | When it fits | Learn more |
|---|---|---|
| Agree and pay or set up a plan | The findings are right or close enough | Paying an audit result |
| IRS Independent Office of Appeals | You disagree and want a settlement-minded review | Agree or appeal |
| U.S. Tax Court | You received a notice of deficiency and still disagree | Notice of deficiency |
| Audit reconsideration | The tax is assessed but you have new records | Audit reconsideration |
- The 30-day letterAgree, disagree or request Appeals
- Notice of deficiencyThe 90-day Tax Court deadline
- Agree or appeal?How to decide
- Tax Court small caseThe simpler S case procedure
- Missing recordsHow to rebuild and support your return
- Self-employed auditsWhat examiners check on Schedule C
- Can’t pay the result?Payment and penalty options after an exam
- IRS Independent Office of AppealsHow an appeal works after an audit
- The Appeals conferencePrepare and argue your case
- Fast Track SettlementSettle with a mediator before the exam closes
- U.S. Tax CourtHow a case works, petition to decision
- File a Tax Court petitionStep by step, before the deadline
- Settle a Tax Court caseMost cases end without a trial
Earned Income Tax Credit audits
Audits of the Earned Income Tax Credit work differently from most exams. Many happen before the refund is paid, and the IRS asks for proof that each child lived with you and is related to you. After a denial you may need to file Form 8862 the next time you claim the credit, and a finding of reckless disregard or fraud can bar the credit for two or ten years.
Get it handled
Many correspondence audits can be answered on your own by sending the records the letter asks for. The IRS explains the process on its IRS audits page. Free help is available from Low Income Taxpayer Clinics if your income qualifies, and from the Taxpayer Advocate Service when an IRS problem is causing hardship.
Representation is worth considering for an office or field audit, when records are missing, when several years are under review, or when the amount at stake is large. If there is any sign the IRS suspects fraud, talk to a tax attorney before answering further questions.
- Do you need representation?What a representative does in an audit
- Missed a deadline?What you can still do
- Who to hireEnrolled agent, CPA or tax attorney
- What happens in a free consultationWhat to bring and what to expect
- Audit deadline calculator30-day, 90-day and statute dates
- IRS letter templatesResponse, protest and release letters
Frequently asked questions
The IRS starts an audit by mail. The IRS says it will not start an audit by telephone. The letter names the tax year and the items under review. A CP2000 notice is a matching proposal, not an audit.
Generally three years from the date the return was filed. It is six years if more than 25 percent of gross income was omitted, and there is no limit for fraud or for a return that was never filed. See how far back the IRS can go.
The IRS can propose changes based on the information it has, then send a notice of deficiency. If you do not petition the Tax Court in time, the tax is assessed and collection notices follow.
Yes. After the exam you can ask the IRS Independent Office of Appeals to review the findings, and after a notice of deficiency you can petition the U.S. Tax Court. See agree or appeal.
Not always. A mail audit asking for a few records can often be answered on your own. A field audit, missing records, several tax years or any sign of fraud are good reasons to get representation.
Sources
- IRS: IRS audits
- IRS: Publication 556, Examination of returns, appeal rights and claims for refund
- IRS: Publication 5, Your appeal rights and how to prepare a protest
- 26 U.S.C. 6501, Limitations on assessment and collection
- 26 U.S.C. 6213, Restrictions applicable to deficiencies; petition to Tax Court
- IRS: Understanding your CP2000 notice
- Taxpayer Advocate Service: Low Income Taxpayer Clinics
We check every figure against IRS.gov and log changes on the key figures page.
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This page is general information about IRS rules, not tax or legal advice for your situation. IRS figures change; each one links to its official source and the date we last checked it.