Short answer
A 30-day letter sends you the IRS audit report and gives you generally 30 days from the letter’s date to respond. You can sign and accept the changes, agree to some of them, or ask the IRS Independent Office of Appeals to review them. If you do nothing, the IRS sends a notice of deficiency, your 90-day Tax Court letter.
Key takeaways
- Letter 525 (generally mail audits), Letter 915 (office audits) and Letter 950 (field audits) are 30-day letters that send you the audit report.
- Signing the agreement form (Form 4549 or Form 870) consents to assessment and gives up your Appeals rights and a notice of deficiency for the items it covers.
- To appeal, send a small case request if each tax period totals $25,000 (IRS.gov, 2026) or less in tax and penalties; above that, a formal written protest is required (Publication 5).
- If you don’t respond, the IRS sends a notice of deficiency with a 90-day Tax Court deadline (150 days if addressed outside the US).
- Interest runs from the return’s due date until you pay, so paying or making a deposit early reduces it even while you dispute.
What the 30-day letter is and what comes with it
The IRS manual calls the 30-day letter a “preliminary letter” used “to transmit the findings of the examination” and to give you 30 days to ask for Appeals consideration (IRM 4.10.8, revised August 28, 2025). You usually get one when the audit is over, the examiner proposes changes, and you have not agreed to them all. Publication 3498, The Examination Process, says you “generally have 30 days from the date of the letter to tell us whether you will accept the proposed changes or appeal them.”
Which letter you get depends on how the audit was done:
| Letter | Typical audit type | What the IRS says about it |
|---|---|---|
| Letter 525, General 30-Day Letter | Audit by mail (correspondence) | Sent with Form 4549 showing the proposed adjustments; sign and return to agree, or request an appeal from the office that sent it |
| Letter 915, Examination Report Transmittal | Office audit at an IRS office | Explains the adjustments; file a protest within 30 days of the letter’s date if you disagree |
| Letter 950, 30-Day Letter (straight deficiency) | Field audit (at your home or business) | Request an appeal from the office that sent it within 30 days of the letter’s date |
The package normally includes:
- The report. Form 4549, Report of Income Tax Examination Changes, has a signature line. Form 4549-A is the same report without one and usually comes with Form 870, a separate waiver you would sign to agree.
- The explanation of each adjustment. Standard explanations, examiner lead sheets or Form 886-A, Explanation of Items, setting out the facts, the law and the IRS’s conclusion for each change.
- Publication 3498. The IRS manual requires it with every 30-day letter.
- An appeal request form where it applies, usually Form 12203, Request for Appeals Review.
Not sure which letter you have? Our guide to IRS audit letters lists them. A CP2000 also gives you a response window, but it is an automated income-matching notice, not an audit report.
Your three choices, side by side
The IRS describes three possible results of an audit: no change, agreed and unagreed. Once you have a 30-day letter, the choices are:
| Option | How | Deadline | What happens next |
|---|---|---|---|
| Agree with everything | Sign and return the agreement form (Form 4549 or Form 870) and pay what you can | The response date on the letter, generally 30 days | The IRS assesses the tax and sends a bill for any unpaid amount; no notice of deficiency for the agreed items |
| Agree in part | Sign a waiver covering only the agreed items; dispute the rest in your appeal request | Same date | The agreed part is assessed; the disputed part goes to Appeals or, if unresolved, to a notice of deficiency |
| Disagree and request Appeals | Small case request or formal written protest, sent to the address on your letter | Same date | The IRS forwards your file to the Independent Office of Appeals, which contacts you to set a conference |
| Do nothing | No response | n/a | A notice of deficiency (90-day letter), then a bill if you don’t petition the Tax Court |
Before choosing, Publication 3498 says you can ask for a meeting or phone conference with the examiner’s supervisor, and you may be able to ask for Fast Track Settlement, a mediation in which an Appeals employee helps you and the examiner settle while the case stays in Examination. Both sides must agree to it, and you keep your normal appeal rights if it fails. Our page on whether to agree or appeal walks through how to decide.
If you agree: what signing means
Signing is more than a receipt. The IRS manual says Form 4549 allows “a taxpayer signature, waiving restrictions on assessment and collection of a deficiency,” and that by signing you indicate you “do not wish to exercise appeal rights” for the adjustments in the report. Form 870 works the same way. Under IRC 6213(d) you may waive those restrictions “in whole or in part.”
In practice, signing means:
- No notice of deficiency for the signed items. The 90-day letter and its prepayment Tax Court route exist only for amounts you have not agreed to.
- The IRS can assess and bill right away. Expect a balance-due notice such as a CP14 for anything unpaid.
- Interest is still owed. Publication 3498 says that if you pay when you sign, interest is generally figured from the return’s due date to the date you pay. Under the IRS manual, if the IRS does not assess and send a bill within 30 days after it receives your signed agreement, interest stops running until it does (IRC 6601(c)).
- It is not always the end. The manual notes that signing a waiver does not stop the IRS from proposing a further deficiency, or you from asking for further consideration. If you later find documents, audit reconsideration may reopen an unpaid assessment.
Sign only what you actually agree with. If one adjustment is wrong, a partial agreement keeps your rights on that item.
If you disagree: small case request or formal protest
Appeals is the IRS’s only level of administrative appeal and is independent of the examiner’s division. Publication 5, Your Appeal Rights and How to Prepare a Protest (Rev. 4-2021), says a formal protest “is required in all cases unless you qualify for a small case request.” The dividing line is the total proposed change in tax and penalties for each tax period in the letter:
| Your case | What to send | What it must contain |
|---|---|---|
| Every tax period totals $25,000 or less in tax and penalties | Small case request | A brief written statement of the disputed issues and why you disagree, or Form 12203, Request for Appeals Review |
| Any one period is over $25,000 | Formal written protest for all periods | Your name, address and daytime phone; a statement that you want to appeal; each disputed issue, period and proposed change with your reasons; the facts; the law you rely on; and a signed penalties-of-perjury statement |
| Partnership or S corporation case, or employee plan and exempt organization case | Formal written protest at any amount | As above |
Publication 5 gives the exact penalties-of-perjury wording, including separate versions for a representative who signs the protest. Send the request to the IRS address on your letter, not to Appeals; the examination office forwards it.
Two points that catch people out:
- Hand over everything first. Publication 5 says new information raised for the first time at Appeals may be sent back to the examiner, which delays the case.
- The statute clock. Appeals generally needs at least 365 days left on the assessment statute when it receives your case. If less remains, the IRS will ask you to sign a consent to extend it (usually Form 872); if you refuse, Appeals will not take the case and the IRS moves to a notice of deficiency. Publication 1035 explains your right to refuse, limit or negotiate the consent.
The IRS Appeals service page explains how a representative prepares a protest.
How to respond to a 30-day letter, step by step
- Read the report and find your date. Find the response date on the letter, then compare every adjustment on Form 4549 or 4549-A and its explanation with your records. Mark each item as agree or disagree.
- Ask the examiner about anything unclear. Call the examiner named on the letter before the due date. You can send more documents or an explanation, and you can ask for a conference with the examiner’s manager.
- Ask for more time if you need it, in writing. If you need longer, call before the due date and follow up in writing with the reason. Extensions are discretionary and usually short.
- Sign for the items you accept. If you agree with everything, sign and return the agreement form. If you agree with only some items, ask the examiner for a waiver (Form 870) covering just those items.
- Request Appeals for the items you dispute. Send a small case request (a brief statement or Form 12203) if each tax period totals $25,000 or less in tax and penalties; otherwise send a formal written protest. Mail it to the address on your letter, not to Appeals.
- Keep proof and calendar the next deadline. Keep copies and proof of mailing or fax. If a notice of deficiency arrives later, its 90-day Tax Court deadline runs on its own and is not extended by talks with the IRS.
If you live outside the United States, the IRS manual tells examiners to allow a reasonable longer period to respond. Ask the examiner what date applies to you.
Asking for more time
Extensions are possible but not a right. The Taxpayer Advocate Service says to call the number on the letter before the due date to ask for more time. Under IRM 4.10.8.12.8, the procedural rules do not provide for an extension, but “as a matter of practice, extensions may be granted under reasonable circumstances,” for example:
- you hired a representative, or a new one, who needs time to prepare a meaningful protest;
- you or your representative are sick or injured; or
- the issues are complex and need research.
Requests should be in writing with your reasons. Extensions are normally no more than 30 days, are confirmed by letter (Letter 686) with the new date, and are not granted if the assessment statute expires within 240 days unless you also sign a statute extension. Get any new date in writing.
What happens if you do nothing
Missing the 30-day letter costs you the cheapest, most informal way to dispute: an Appeals conference before anything is assessed. You can still go to Tax Court (and Publication 5 says you will normally get a chance to settle with Appeals while your case waits for trial), but the 90-day deadline is fixed by law. Read how the notice of deficiency works before it arrives. Mail audits end with Letter 3219 and in-person audits with Letter 531; a CP3219A is the version that follows an income-matching review rather than an audit.
If both deadlines have already passed, see what you can still do after a missed audit deadline.
Paying now, paying later, or paying while you appeal
Interest runs on any additional tax from the return’s original due date. The rate is the federal short-term rate plus 3 percentage points, reset quarterly (7% (IRS.gov, Jul-Dec 2026) this quarter); see how IRS interest works. Penalties in the report, if any, are added to the tax.
- While you dispute. Publication 3498 says you can stop interest on the amount you expect to owe by making an advance payment or an IRC 6603 deposit. Interest stops on that part when the IRS receives the money, though interest already accrued keeps compounding.
- After you agree. Publication 3498 says that if the total due (including interest and penalties) is under $100,000 (IRS.gov, 2026) and you pay within 21 calendar days of the bill, no more interest or penalties are added; at $100,000 or more the window is 10 business days.
- If you can’t pay. Pay what you can and ask for a payment plan. If you owe $50,000 (IRS.gov, July 2026) or less, a Simple Payment Plan (formerly the streamlined installment agreement) usually needs no financial statement; see IRS payment plans compared and options when you can’t pay an audit bill.
Doing it yourself, free help, and when a representative is worth it
A one-issue mail audit where you have the missing receipt can often be handled alone: send the document, or sign for what you accept and file a short small case request for the rest. A representative adds more when the proposed change is large enough to need a formal protest, several years or business income are involved, penalties are proposed, or the IRS asks you to extend the statute.
- Taxpayer Advocate Service: free help when an IRS problem causes financial hardship or normal channels have failed, 877-777-4778 (IRS.gov, 2026) or taxpayeradvocate.irs.gov.
- Low Income Taxpayer Clinics: LITCs can represent eligible taxpayers in audits and appeals for free or a small fee.
- A representative: an attorney, CPA or enrolled agent can attend the Appeals conference for you under a Form 2848 power of attorney.
Global Gate Tax Relief offers a free consultation and reviews the audit report and your IRS transcripts before recommending whether to agree, protest or wait for the notice of deficiency. If it takes the case, it quotes a flat fee upfront and does not promise a result. Request a free review of your 30-day letter or call 1-877-800-8180.
Frequently asked questions
It is the letter that sends you the IRS audit report and gives you generally 30 days from its date to agree or ask for an appeal. Common versions are Letter 525 (generally mail audits), Letter 915 (office audits) and Letter 950 (field audits).
No. Letter 525 is a 30-day letter that proposes changes and offers an Appeals review. A notice of deficiency (Letter 3219 after a mail audit, Letter 531 after an in-person audit) comes later if you don’t respond or don’t settle, and starts the 90-day Tax Court deadline.
Sometimes. Call the number on the letter before the due date and follow up in writing with your reason. The IRS grants extensions in reasonable circumstances, usually for no more than 30 days, and may require you to extend the assessment statute if little time is left on it.
You consent to the IRS assessing and collecting the tax in the report and give up your Appeals rights and a notice of deficiency for those adjustments. The IRS then bills you for anything unpaid, with interest from the return’s due date.
Only if the proposed change in tax and penalties is more than $25,000 for any tax period, or for partnership and S corporation cases at any amount. Otherwise a small case request is enough: a short written statement or Form 12203 listing what you disagree with and why.
Yes. The IRS uses Form 870 as a waiver in partially agreed cases. You sign for the agreed items, which are assessed, and the unagreed items follow normal appeal procedures.
The IRS sends a notice of deficiency. You then have 90 days from its date (150 days if addressed outside the US) to petition the Tax Court; if you don’t, the tax is assessed and billed.
Sources
- IRS Publication 3498, The Examination Process (Rev. 5-2025)
- IRS Publication 5, Your Appeal Rights and How to Prepare a Protest if You Disagree (Rev. 4-2021)
- IRM 4.10.8, Report Writing (08-28-2025)
- IRS: Letters and notices offering an appeal opportunity (reviewed 16 Jul 2026)
- Taxpayer Advocate Service: Letter 525 (updated 14 Jul 2026)
- IRS Publication 1035, Extending the Tax Assessment Period (Rev. 9-2017)
- 26 U.S.C. 6213, Restrictions applicable to deficiencies; petition to Tax Court
- IRS: Quarterly interest rates
- IRS: Low Income Taxpayer Clinics
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