IRS Audit Types and How to Respond: Mail, Office and Field Audits

Knowing the IRS audit types and how to respond to each one is the best protection against a bad outcome. An IRS audit is a review of your books, accounts and records to confirm that the return you filed is correct. Selection does not mean the IRS found a problem, and many audits end with no change. Whether you run a business in Aurora, rent out property in Pune or hold accounts in Toronto, the process follows the same path: a letter, a request for records, a report of findings and, if you disagree, a right to appeal.

How does the IRS select a return for audit?

The IRS says it uses several methods: random selection and computer screening that compares your return against norms for similar returns, and related examinations, where your return is chosen because of transactions with another taxpayer, such as a business partner or investor, who is being audited. Filing an amended return does not affect the selection of the original return, although amended returns go through their own screening, and a refund by itself is not necessarily a trigger.

IRS audit types and how to respond to each

The letter will contain the contact details and instructions. The IRS also keeps a list of the records it may ask for. The law requires you to keep the records you used to prepare your return for at least three years from the date the return was filed, and longer in some cases (see the deadlines section).

How to respond to an IRS audit step by step

1. Read the letter and calendar the response date. Note the tax years, the items under review and the examiner's contact information.
2. Authorize a representative early. If you want a CPA, attorney or enrolled agent to handle the audit, file Form 2848. Publication 1 lists the right to representation, by yourself or an authorized representative. See authorized representatives by country.
3. Build the document set. Gather bank and card statements, invoices, mileage logs, leases, closing statements and anything that shows the item and the amount. Organize it in the order of the request.
4. Answer only what is asked. Provide copies, label each exhibit and keep a duplicate set.
5. Ask for more time in writing if needed. For a mail audit, fax your written request to the number on the letter, or mail it if you cannot fax. A notice of deficiency received by certified mail is different: the IRS says it cannot grant additional time to submit documentation after that.
6. Confirm delivery. Use delivery confirmation for anything you mail. Some audits can be tracked in your IRS online account.
7. Review the findings. The audit ends in one of three ways: no change, agreed or disagreed.

What happens if I do not respond?

If you do not respond by the date shown, the IRS says it will complete the audit and send an audit report with proposed changes to your return. The next steps then run on fixed deadlines, so silence usually costs more than an incomplete answer.

Deadlines and look-back periods

In its 2026 guidance, the IRS says it generally includes returns filed within the last three years in an audit, may add years if it finds a substantial error, and usually does not go back more than six years. The time the IRS has to assess additional tax is generally three years after the return was due or filed, whichever is later. Records guidance adds that the period is six years if you omit income that is more than 25 percent of the gross income on your return, and unlimited if you do not file a return or file a fraudulent one.

You are not required to agree to extend the assessment period, but if you do not, the examiner will decide based on what you have provided. Publication 1035 explains extensions. For foreign information such as an unreported specified foreign financial asset, longer rules can apply; see our foreign reporting penalties guide and the audit timelines by country.

What are your appeal rights after an audit?

• Agree. You sign the examination report or waiver form and pay any balance. Payment options are described in Publication 594.
• Disagree. You can request a conference with an IRS manager. The IRS also offers mediation, and you can file an appeal if enough time remains on the statute of limitations.
• 30-day letter. Within a few weeks of the closing conference the IRS sends a package with a letter giving you 30 days to accept or appeal, an examination report and a waiver form. For a total of $25,000 or less for any tax period, you can file a small case request instead of a formal written protest.
• 90-day letter. If you do not respond or you do not reach agreement with Appeals, the IRS sends a notice of deficiency. You have 90 days to petition the Tax Court, or 150 days if the notice is addressed to you outside the United States. A small tax case procedure is available if the amount at issue is $50,000 or less for each tax period.
• Audit reconsideration. If an audit assessment stands and you have new information, the IRS has a process to request a review; see its audit reconsideration page.

The IRS Independent Office of Appeals is separate from the examiner and tries to resolve disputes without litigation.

Audits that involve foreign accounts and assets

A foreign bank account report (FBAR) examination can begin as a result of an income tax examination, and Form 2848 can cover it if you describe the matter as relating to the Report of Foreign Bank and Financial Accounts. If you hold accounts or entities abroad, expect questions about statements, ownership and why a form was or was not filed. Our FBAR guide explains the report.

A worked example

Jenna runs a graphic design practice from Aurora. In September 2026 she receives a letter asking for support for $6,800 of vehicle expenses and $2,400 of meals on her 2024 Schedule C. She asks for the extension in writing, reconstructs a mileage log from calendar entries and gas receipts, and mails copies with a cover note. The examiner accepts the meals but disallows $4,000 of vehicle expense because the log is incomplete. Jenna disagrees, asks for a manager conference and, with the total under $25,000, can use a small case request to appeal. The numbers are hypothetical.

Mistakes to avoid

• Calling an unexpected caller back. The IRS does not start audits by phone.
• Handing over originals or entire filing cabinets.
• Volunteering information that is not requested.
• Missing the 30-day or 90-day deadlines after the report arrives.
• Signing an extension of the assessment period without understanding it.

How we can help

Our firm represents clients before the IRS and Illinois Department of Revenue from our Aurora, Illinois area base, including mail, office and field audits. We prepare the document set, attend meetings and handle appeals. When the audit touches Canadian or Indian income, we coordinate with your Canadian CPA or Indian Chartered Accountant. No result is guaranteed. See IRS and state tax representation and bookkeeping and record retention. Browse the notices hub for every guide in this series.

Frequently asked questions

General information only. It is not tax, legal, accounting or immigration advice for your situation, and rules change; confirm the current rules with the official source or a licensed professional in the relevant country.