IRS Audit Letters Explained

Audit letters and forms at a glance

Find the number on your letter, then the row below. Every letter and form here was checked against IRS.gov, the IRS manual or the Taxpayer Advocate Service on October 25, 2026. When this table and your letter differ, the date printed on your letter controls.

Audits move in a fixed order: a first-contact letter, document requests, a report, a 30-day letter if you don’t agree, and a notice of deficiency if the disagreement remains. Knowing where your letter sits in that order tells you how much time you have. Not sure which kind of audit you are in? See types of IRS audits.

Each letter and form has a full page with what to send and what happens next:

• Letter 566Mail audit has started
• Letter 2205-AField audit contact
• Letter 3572Office audit: call to schedule
• 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

Letters that start an audit: 566, 3572, 2202, 2205

Letter 566 (mail audits)

The Taxpayer Advocate Service lists a whole family of initial contact letters under this number, including 566-S (generally an audit of a specific item) and 566-E (wages, withholding and refundable credits). Each lists the items being questioned and asks you to document them by the due date on the letter. Some include questionnaires to fill in and return. If you don’t respond, “the items in question will be disallowed” and the IRS sends an examination report showing the proposed changes.

Two versions, 566-B and 566-J, combine the first contact with the report itself (Form 4549). TAS says these give you “30 or 45 days (from the date of the letter)”; check which one is printed on yours. To keep your right to an Appeals conference, request it before the response date in the letter.

Letter 3572 and Letter 2202 (office audits)

Under IRM 4.10.2 (revised August 28, 2025), tax compliance officers open office audits with Letter 3572, which asks you to call and schedule an appointment, or Letter 2202, which sets “a firm initial appointment date and time.” A Form 4564 listing the records to bring goes with the letter.

Letter 2205 and Letter 2205-A (field audits)

Revenue agents open field audits with Letter 2205, which “does not list the issues being examined,” or Letter 2205-A, which does. The manual tells examiners to allow 14 calendar days for a response, including mailing time, and a minimum of 10 business days to secure a representative. It also requires that all initial contacts to start an exam be made by mail, with Publication 1, Your Rights as a Taxpayer, enclosed.

During the audit: Form 4564, the Information Document Request

Form 4564 is how an examiner asks for records. IRM 4.10.2 says it “will list the specific records, information, and documents” you should have ready, and it “must always include a date for submission.” In office audits it comes with the first letter; in field audits it is generally sent with the appointment confirmation letter. More than one IDR is common as an audit develops.

• Send exactly what is listed, as copies, organized by item. Publication 3498-A says not to send originals.
• If you can’t meet the date, call the examiner before it passes and ask for more time.
• If a record is lost, say so and explain how the amount was figured; Publication 3498-A tells mail-audit taxpayers to “provide an explanation of the issue and how the amount was determined.” See rebuilding missing records.

The audit report: Forms 4549, 4549-A, 886-A and 870

When the examiner proposes changes, the findings arrive as a report. The IRS manual (IRM 4.10.8, revised August 28, 2025) describes the pieces:

• Form 4549, Report of Income Tax Examination Changes, is “the basic report form for most individual and corporate income tax cases.” It has a signature line. Signing it waives the restrictions on assessment and collection of the deficiency, and “by signing, the taxpayer is indicating they do not wish to exercise appeal rights.” Don’t sign if you disagree or plan to appeal.
• Form 4549-A shows the same kind of changes but “does not have a place for the taxpayer(s) to sign.” It is used for unagreed and some other cases.
• Form 886-A, Explanation of Items, explains the facts, law and conclusions behind an adjustment (IRM 4.10.10). Office audits attach it when an adjustment needs a longer explanation, large-business audits generally use one for each adjusted issue, and field examiners may use lead sheets or other workpapers instead. See Form 886-A explained. It is where you find the IRS’s facts and reasoning for each change, so read it line by line.
• Form 870 is a waiver of restrictions on assessment and collection. The manual says it is used as the waiver “in partially agreed cases” and that signing it does not stop the IRS from asserting a further deficiency.

Whether to sign is the key decision of the whole audit. Our guide to agreeing or appealing walks through it.

30-day letters: Letter 525, Letter 915 and Letter 950

A 30-day letter sends you the report and your appeal rights. The IRS Independent Office of Appeals lists Letter 525 (“General 30-Day Letter”), Letter 915 (“Examination Report Transmittal”) and Letter 950 (“30-Day Letter-Straight Deficiency”), each with 30 days from the letter date to request Appeals.

Your choices are the same for all three: sign and return the agreement, send more documents or an explanation, ask for a conference with the examiner’s manager, or request Appeals. A smaller dispute can use a short small case request (Form 12203); a larger one needs a formal written protest. The dollar limit and what a protest must contain are in our 30-day letter guide. If you need more time, call the number on the letter before the due date.

If you don’t respond, the IRS may disallow the items and issue a notice of deficiency (TAS, Letter 525 page).

Notices of deficiency: Letter 3219, Letter 531 and CP3219A

The statutory notice of deficiency, often called the 90-day letter, is the most important letter in an audit. TAS says Letter 3219 is sent after a mail audit and Letter 531 after an in-person audit. CP3219A is the version for income mismatches, and IRS.gov says it is sent because “information we received from others like your employer or bank” differs from your return.

If you agree, you can sign Form 5564, the notice of deficiency waiver. If you neither agree nor petition, the IRS assesses the tax and sends you a bill for the amount due (our CP14 guide explains a first balance-due notice). After that, TAS says, a judge can’t review the case unless you first pay. Read notice of deficiency: your Tax Court deadline and the CP3219A guide.

Letters that look like audits but aren't

A CP2000 proposes changes when third-party income information doesn’t match your return. The Taxpayer Advocate Service says it “is not an IRS audit or a bill,” though ignoring it leads to a CP3219A. CP2501 is an earlier mismatch letter. CP11 and CP12 are math-error corrections with their own short window to dispute. Types of IRS audits explains the difference.

How to check that an audit letter is real

Scammers copy IRS letters. A few checks catch most fakes:

1. Mail comes first. The IRS says it notifies you of an audit by mail and “won’t initiate an audit by telephone.” A first contact by phone, text or email is a warning sign.
2. Check your IRS Online Account. The IRS audits page says you can see audit status, letter dates and response due dates under “Records and Status.”
3. Call the IRS, not the number in a suspicious letter. Use the number on IRS.gov, such as 800-829-1040 (IRS.gov, 2026) for individuals, and ask whether an exam is open.
4. Payment goes only to the United States Treasury. Publication 3498 says checks are payable to the “United States Treasury.” Demands for gift cards or wire transfers to anyone else are not IRS practice.

More signs to look for are in how to spot fake IRS letters.

Answering yourself, free help, and representation

You can answer any of these letters yourself: by mail, by fax, or through the IRS Document Upload Tool when the letter gives you an access code. Low Income Taxpayer Clinics represent eligible taxpayers in audits and appeals for free or a small fee, and the Taxpayer Advocate Service (877-777-4778 (IRS.gov, 2026)) helps when an IRS problem is causing financial hardship. A representative (attorney, CPA or enrolled agent) can take over the letters under a Form 2848.

Not sure what your letter means? Free review or call 1-877-800-8180. Global Gate Tax Relief tells you whether you can handle the letter yourself and, if it takes the case, quotes a flat fee upfront. No outcome is guaranteed.

Frequently asked questions

Keep reading in the IRS Audit Guide

• Types of IRS auditsMail, office and field audits compared.
• First steps after an audit letterWhat to do in the first 10 days.
• The 30-day letterYour three choices and how to request Appeals.
• Notice of deficiency (90-day letter)The Tax Court deadline and how to petition.
• Agree or appeal?How to decide whether to sign the audit report.