IRS Audit: What to Expect and How to Prepare

By Tom, CPA · Updated October 27, 2026

Part of: Tax Planning

TL;DR: Most individual audits are by mail and limited to specific items. Respond by the deadline with organized copies, know your rights to representation and appeal, and remember the usual 3-year statute.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

The word "audit" conjures images of stern agents in windowless rooms, flipping through shoeboxes of receipts while a clock ticks loudly. Reality is usually far duller: a letter asking you to mail copies of a few documents, followed by weeks of waiting and, often, either no change or a modest adjustment. The tax code is 4 million words long; you need about 400 of them to understand how audits work, what the odds really look like, and how to prepare.

This guide covers the types of IRS examinations, what the IRS says about audit rates, document prep, your rights as a taxpayer, and the statute of limitations. Procedures described are as of Oct 2026. If you have received a letter but are not sure whether it is an audit, start with our IRS notice guide; many letters, like the CP2000, are automated proposals rather than examinations.

CPA Warning Label: Audits of aggressive positions (REPS, STR loophole, S corp salary) hinge on records made at the time. Build the file now, not after the letter.

Audit types

Correspondence audit

The most common type for individuals. Conducted entirely by mail. The IRS asks for documentation of specific items, such as charitable contributions, a credit, or business expenses. You respond with copies and an explanation.

Office audit

You are asked to meet with an IRS employee at a local office, usually about a limited set of issues listed in the letter. You can bring a representative.

Field audit

An IRS revenue agent visits your home, business or representative's office. More common for businesses and complex returns, and broader in scope.

Not audits, but often confused with them

• Math error notices (CP11, CP12) adjust obvious computation issues.
• Automated underreporter notices (CP2000) propose changes from mismatched 1099s and W-2s.
• Identity verification letters (5071C) confirm you filed a return.

The IRS says it initiates audits by mail. A legitimate audit is never started by an unexpected phone call demanding payment.

The odds

Audit rates for individual returns are low overall. IRS Data Book figures over recent years have shown examination rates well under 1% of individual returns, with higher rates for very high incomes and for some returns claiming the Earned Income Tax Credit. Because returns can be examined for several years after filing, rates for recent years can rise as audits are completed. For current figures, check the latest IRS Data Book; we do not quote a single number here because it changes year to year.

What tends to draw attention, based on IRS-described compliance focus areas:

• Income not matching information returns.
• Large or unusual deductions relative to income.
• Schedule C businesses with repeated losses, high vehicle or meal expenses, or round numbers.
• Refundable credits claimed without documentation.
• Cash-intensive businesses.
• Very high incomes and complex pass-through structures.
• S corporations with little or no officer salary.
• Aggressive real estate positions like real estate professional status or the short-term rental loophole.

Low odds are not a strategy. The right approach is to file positions you can document, so that an audit, if it comes, is a paperwork exercise.

Document prep

Start the moment the letter arrives:

1. Read the scope. The letter lists the items and years under review. Respond to those, not to everything.
2. Pull the return and the workpapers or software file behind it.
3. Gather source documents for each item: receipts, invoices, bank and card statements, mileage logs, appraisals, charitable acknowledgment letters, closing statements, depreciation schedules.
4. Organize by issue. One tab or folder per item, with a short summary page showing how the documents add up to the number on the return.
5. Send copies, never originals. Label each page with your name, SSN and tax year.
6. Meet the deadline, or ask for more time before it passes.
7. Keep a log of every contact: date, name, ID number of the IRS employee, what was discussed.

Reconstructed records can be acceptable if contemporaneous records were lost, but they must be reasonable and supported. "I definitely drove 22,000 business miles" with no log is not a reconstruction; it is a wish. Bank and card statements, calendars, emails with clients and toll records can corroborate a reconstruction, and the more independent evidence you have, the better it holds up. See how long to keep tax records.

Your rights

The Taxpayer Bill of Rights lists 10 fundamental rights, including the right to be informed, to quality service, to pay no more than the correct amount of tax, to challenge the IRS's position and be heard, to appeal in an independent forum, to finality, to privacy, to confidentiality, to retain representation, and to a fair and just tax system.

In practice:

• Representation: you can have a CPA, enrolled agent or attorney represent you, using Form 2848. You generally do not have to attend meetings yourself if represented.
• Appeals: if you disagree with the examiner's findings, you can request a conference with the IRS Independent Office of Appeals.
• Tax Court: after a statutory notice of deficiency (a "90-day letter"), you can petition the U.S. Tax Court without paying first, but the 90-day deadline is strict.
• Taxpayer Advocate Service: free help when the process is stuck or causing hardship.

Statute of limitations

The IRS generally has three years from the date you filed (or the due date, if later) to assess additional tax. Key exceptions:

The IRS may ask you to extend the statute during an audit. You can negotiate scope, but refusing may lead the IRS to issue a notice of deficiency based on what it has. Discuss with a representative. Keep in mind that your own deadline to claim refunds runs on a similar clock: generally three years from filing or two years from payment, whichever is later.

How audits end

An examination usually closes in one of three ways:

• No change. The IRS accepts the return as filed and sends a letter saying so. This is more common than people assume when records are solid.
• Agreed. The examiner proposes adjustments, you agree, and you sign a form (often Form 4549). You pay or set up a payment plan. Interest runs from the original due date.
• Unagreed. You disagree. You can ask to speak with the examiner's manager, request Appeals, and ultimately go to Tax Court after a notice of deficiency.

Penalties often come up at the end. The accuracy-related penalty is generally 20% of the underpayment attributable to negligence or a substantial understatement. Reasonable cause and good-faith reliance on a qualified professional can be defenses. Documentation is your best evidence of good faith.

If an audit finds you overpaid, which does happen, you get a refund with interest.

Should you get help?

For a simple correspondence audit about one or two documented items, many people handle it themselves. Consider a representative when the amount is large, the issues involve judgment (business expenses, real estate professional status, valuation, cost segregation), the audit expands to more years, or you feel stuck. A representative also keeps you from volunteering information outside the scope, which is the most common self-inflicted wound in audits. Low-income taxpayers may qualify for free help through Low Income Taxpayer Clinics.

Illustration: a correspondence audit

Jesse receives Letter 566 questioning $9,800 of charitable contributions and $6,200 of Schedule C vehicle expenses on a 2024 return. Jesse sends:

• Written acknowledgments from charities for each gift of $250 or more, plus bank records for smaller ones.
• A mileage app export showing 8,857 business miles at the 2024 rate of 67 cents (about $5,934), with purposes noted.

The vehicle number on the return was slightly overstated. The examiner accepts the charitable deductions in full and reduces vehicle expenses to the logged amount. The result: a small increase in tax plus interest. No penalty, because the error was small and documented good faith. Illustrative only, using the 2024 mileage rate from the IRS mileage table.