If you just opened a letter from the IRS proposing changes to your return, here is how to respond to an IRS audit notice: verify the letter is genuine, answer only the items it lists, send organized documentation before the deadline printed on the notice (usually 30 days), and use certified mail or an approved private carrier so you can prove it arrived. Everything else in the process, from penalties to appeals, flows from that first reply.
Confirm the Letter Is Actually From the IRS
The IRS always opens an audit by mail. It will never start one with a phone call.1Internal Revenue Service. IRS Audits If someone calls claiming to be an examiner and no letter has arrived, that call is not the IRS.
A real notice shows a partially masked taxpayer identification number, the specific tax years under review, a response deadline, and a named examiner or unit with direct contact information. You can verify anything you received by signing into your IRS online account, where audit activity appears under the Records and Status tab, or by calling the number printed on the letter itself. Do not call a number from a search result or from anyone who contacted you.1Internal Revenue Service. IRS Audits
Read the Notice: What Type, What Scope, What Deadline
The letter tells you three things you need before you do anything else: what kind of audit this is, which line items the IRS is questioning, and how long you have to respond.
The Three Audit Types
A correspondence audit is handled entirely by mail and usually targets one or two items, such as a charitable deduction or a 1099 mismatch. An office examination requires you to bring records to a local IRS office. A field examination sends an agent to your home or business and is the most comprehensive.
Notice Numbers That Tell You What Stage You’re In
A CP2000 (and its relatives CP2501, Letter 2030, and Letter 2531) means the IRS found a mismatch between what you reported and what a third party — an employer, bank, or brokerage — reported for you. These are handled by mail.2Internal Revenue Service. Understanding Your CP2000 Series Notice A Letter 525 is the standard 30-day letter sent after an examiner has completed a review and is proposing changes.3Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond A CP3219N is a Statutory Notice of Deficiency, the 90-day letter that opens the door to Tax Court.4Internal Revenue Service. Understanding Your CP3219N Notice
Answer Only What Was Asked
Your notice lists the specific line items in question. Your reply addresses only those items. Volunteering information about anything else can expand the audit’s scope and create issues that didn’t exist before, and it almost never helps.
The Deadline Is Not Flexible on Its Own
The 30 days the notice gives you is real. Miss it and the IRS can adjust your return automatically, assess additional tax, and start adding penalties and interest that become progressively harder to unwind. If you need more time, call the examiner using the number on the letter before the deadline and ask. Do not go silent.
Decide Whether Someone Else Will Handle It
You can respond on your own, or you can bring in a tax professional. If you want a CPA, attorney, or enrolled agent to speak with the IRS on your behalf, they need a completed Form 2848 (Power of Attorney and Declaration of Representative). Both of you sign it, and the form has to name the tax matters and periods covered.5Internal Revenue Service. About Form 2848, Power of Attorney and Declaration of Representative6Internal Revenue Service. Instructions for Form 2848, Power of Attorney and Declaration of Representative Without a valid 2848 on file, the IRS cannot discuss your case with anyone but you. Include the form with your response so the representative can act immediately.
If cost is the obstacle, Low Income Taxpayer Clinics provide free or low-cost representation, and you retain the right to counsel of your choosing under the Taxpayer Bill of Rights.7Internal Revenue Service. Taxpayer Bill of Rights
Build the Response Package
A well-organized reply is the difference between a quick close and months of follow-up letters. The examiner reading your case is handling many others at the same time. Make it easy for that person to confirm your position.
Documents
Pull together legible copies of every record that supports the items being questioned: bank statements, receipts, invoices, canceled checks, contracts, third-party confirmations. Send copies, never originals. The IRS is not responsible for returning them.
Label each document to tie it directly to the line item on the notice. If the IRS is questioning your Schedule C office expenses, group those receipts behind a cover sheet marked “Schedule C, Line 18 — Office Expenses.” Tedious, yes. It also dramatically reduces the chance the examiner misses your evidence and proposes changes you already addressed.
The Cover Letter
Open with a short, professional letter listing the notice number, tax year, and your taxpayer identification number. The letter is the table of contents for the package. Walk through each questioned item in order. State your position in one or two factual sentences. Point to the specific supporting documents enclosed. Keep the tone neutral; emotional arguments and unrelated personal details work against you. Close by stating that the enclosed documentation supports the figures on your original return.
Reasonable Cause, If Penalties Are Likely
If the audit is heading toward penalties, include a written explanation in the same package asking that penalties be waived. The IRS asks whether you used ordinary care and prudence but were unable to comply due to circumstances beyond your control.8Internal Revenue Service. Introduction and Penalty Relief Serious illness or death in the immediate family, a fire or natural disaster that destroyed records, reliance on incorrect professional advice, and inability to obtain records despite reasonable efforts all count. The examiner will also look at your compliance history for the prior three years and how quickly you corrected the problem once you found it. Document dates, names, and evidence. It is much easier to prevent a penalty than to remove one after assessment.
If your compliance record is clean for the three years before the year under review, ask for First Time Abate as well. It covers failure-to-file and failure-to-pay penalties (not the accuracy-related penalty) when all prior returns are filed and there are no penalties in the prior three years.9Internal Revenue Service. Administrative Penalty Relief
Send It So You Can Prove It Arrived
How you deliver the response matters almost as much as what is in it. The goal is undeniable proof the IRS received your package before the deadline.
Delivery
USPS Certified Mail with Return Receipt Requested is the standard. The green card gives you a signature, delivery date, and confirmation the IRS has your package. The IRS also accepts designated services from FedEx, UPS, and DHL under the timely-mailing-is-timely-filing rule, but only specific tiers qualify, such as FedEx Priority Overnight, UPS Next Day Air, and DHL Express.10Internal Revenue Service. Private Delivery Services Not every service from those carriers is on the approved list.
Send it to the exact address printed on the notice. Mailing to a general processing center causes delays and can make the response look untimely. Some correspondence audits now allow digital submission through an IRS portal; the notice will tell you if that option is available.
Keep a Complete Copy
Before you seal the envelope, copy or scan every page: cover letter, all documents, and the original notice. Once you mail it, clip the mailing receipt, tracking number, and returned green card to that file. This is your record if the case moves to Appeals or Tax Court. The IRS generally recommends keeping records for at least three years from the filing date, and for audit-related documents, at least three years after the case is fully resolved is safer.11Internal Revenue Service. How Long Should I Keep Records
Follow Up
Track the shipment. Once delivery posts, you have proof of receipt. After the deadline passes, expect one of three things: a request for more information, a notice of proposed adjustment, or a closing letter. If a few weeks go by with nothing, call the examiner on the number listed in your notice to confirm receipt and ask about the timeline. Letting the case go dormant risks an automatic assessment based on whatever the IRS already has on file.
The Statute of Limitations and Form 872
The IRS generally has three years from your filing date to assess additional tax. Filing early doesn’t shorten that; the clock starts on the filing deadline.12Office of the Law Revision Counsel. 26 USC 6501 Limitations on Assessment and Collection That window grows to six years if you omitted more than 25% of your gross income, and there is no limit at all on unfiled or fraudulent returns.13Internal Revenue Service. Time IRS Can Assess Tax
During the audit, the examiner may ask you to sign Form 872 to extend that deadline by mutual consent.14Internal Revenue Service. Extension of Assessment Statute of Limitations by Consent You are not required to sign. Signing gives you more time to gather evidence and negotiate, and it gives the IRS more time to keep digging. Refusing may prompt the examiner to issue a quick assessment based on what is already in the file, which can be worse than a longer, fully documented review. This is a good moment to talk to a tax professional before deciding.
If You Disagree With the Examiner’s Findings
Disagreeing does not mean you lose. The IRS runs a structured dispute process, and most cases settle before court.
The 30-Day Letter
When the examiner finishes and proposes changes you don’t accept, the IRS issues a 30-day letter with the examiner’s report and a waiver form. You have three choices: sign the waiver and accept the changes, request a conference with the IRS Independent Office of Appeals, or do nothing.3Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond Doing nothing is almost always a mistake. The IRS will escalate and issue a statutory notice of deficiency, which starts a hard 90-day clock. If you need more time, call the number on the letter before the deadline.
Fast Track Settlement
Before formal Appeals, you can try Fast Track Settlement, which brings an Appeals officer in to mediate while the case is still with the examiner. The target resolution is 60 days.15Internal Revenue Service. Fast Track You apply on Form 14017 through your examiner. Both sides must agree and either can withdraw. It works best on judgment calls rather than clear-cut legal questions.
Formal Appeals
If the amount in dispute for each tax period is $25,000 or less, you can file a small case request on Form 12203, a one-page form listing the items you disagree with and your reasons.16Internal Revenue Service. Preparing a Request for Appeals Above $25,000, you must submit a formal written protest within the 30-day window. The protest needs your name, address, and TIN; a statement that you want to appeal; the tax periods and amounts; a detailed statement of facts; and the legal basis for your position. Using the wrong format for your dollar amount can delay the case by weeks.
Appeals is independent of the examination division and reviews the case fresh. Appeals officers can settle based on the hazards of litigation, which means they can split the difference when both sides have reasonable arguments.7Internal Revenue Service. Taxpayer Bill of Rights
The 90-Day Letter
If you skip the 30-day letter or Appeals cannot resolve the case, the IRS issues a Statutory Notice of Deficiency, the 90-day letter. You have exactly 90 days from the date on the notice to file a petition with the U.S. Tax Court (150 days if you are outside the country).4Internal Revenue Service. Understanding Your CP3219N Notice Miss that deadline and the IRS can assess immediately. Your only remaining option is to pay in full and sue for a refund in U.S. District Court or the Court of Federal Claims, which is slower, more expensive, and requires the money upfront.
What Extra Tax Actually Costs
If the audit ends with additional tax owed, interest and often penalties come with it. Interest on underpaid tax runs from the original due date of the return, not the date the audit closes, and it compounds daily.17eCFR. 26 CFR 301.6622-1 Interest Compounded Daily The IRS sets the rate quarterly.18Internal Revenue Service. Quarterly Interest Rates Interest cannot be abated for reasonable cause; it runs until the tax is paid.
The most common audit penalty is the accuracy-related penalty, which adds 20% to the underpayment caused by negligence or a substantial understatement of income tax.19Office of the Law Revision Counsel. 26 USC 6662 Imposition of Accuracy-Related Penalty on Underpayments A “substantial understatement” generally means the understated amount is more than the greater of 10% of the correct tax or $5,000. Fraud carries a 75% penalty, but that requires intentional wrongdoing, not an honest mistake. Reasonable cause relief, unlike First Time Abate, can apply to the accuracy-related penalty, which is why the written explanation belongs in your original response rather than after the assessment.8Internal Revenue Service. Introduction and Penalty Relief
If Your Case Stalls, Call the Taxpayer Advocate
The Taxpayer Advocate Service is an independent organization inside the IRS. File Form 911 if the audit is causing economic harm, the IRS has not responded within its normal timeframes, or a system or process is not working as it should.20Internal Revenue Service. Taxpayer Advocate Service Case Criteria Economic harm includes threats to your ability to pay for basic necessities, imminent adverse actions like a levy, or significant professional fees you will incur if the issue is not resolved quickly. Systemic delays qualify after the IRS has been unresponsive for more than 30 days beyond its normal processing time. The Advocate cannot change tax law, but it can move a case that is stuck.
Don’t Forget Your State Return
A federal audit adjustment almost always changes your state income tax too. Most states require an amended state return within a set window after the federal changes become final, and that window varies: some states give 90 days, others 120, and a few up to a year. Missing the state deadline triggers separate state penalties and interest on top of what you owe the IRS. Once your federal case closes, check with your state’s revenue department for the specific deadline and forms.