If you want to know how to respond to an IRS audit notice, the short version is this: find the deadline printed on the letter, identify which notice you received, send the specific documents it asks for by certified mail or the IRS Document Upload Tool before that date, and keep proof of everything you send. The rest is detail, but the detail matters, because the type of notice controls what you owe the IRS in return and what happens if you get it wrong.
Identify Which Notice You Received
Every IRS audit starts with a letter. The agency will never open an examination by phone call or email, so unsolicited contact through those channels is almost certainly a scam. The notice number is printed in the upper right corner of the letter, and it tells you what kind of examination you’re facing.
A CP2000 is not technically a full audit. It’s an automated notice that arrives when income reported by an employer, bank, or brokerage doesn’t match what appears on your return. The letter shows the discrepancy and proposes an adjustment. You may owe more, less, or nothing different once you check the numbers.1Internal Revenue Service. Understanding Your CP2000 Series Notice
Letter 566 is the most common audit notice for individuals. It opens a correspondence audit, handled entirely by mail. The letter identifies the specific line items under review — a charitable deduction, a credit, a business expense — and asks for supporting documents for those items only. The examiner is not looking at your whole return.2Taxpayer Advocate Service. Letter Notifying Taxpayer of Audit with Request for Additional Information
Letter 2205 is the initial contact letter for an in-person examination. An office audit asks you to bring records to an IRS office; a field audit sends a revenue agent to your home, business, or accountant’s office. Field audits tend to involve larger dollar amounts, business returns, or situations where the agent needs to see records or operations firsthand.3Internal Revenue Service. IRS Audits
Letter 525, the 30-day letter, arrives after the examination is finished. It gives you 30 days to accept the IRS’s proposed changes or file a written protest and request a conference with the Independent Office of Appeals.4Taxpayer Advocate Service. Letter 525, General 30-Day Letter
Read the Deadline off the Letter
Most audit notices give you 30 days from the date printed on the letter to respond. Not the date you opened the envelope. Not the date the mail arrived. The date on the notice, because that is the date the IRS uses.
If you cannot meet the deadline, call the number on the notice before it passes. Examiners can often grant extensions, but only if you ask before the clock runs out. Silence is not a request for more time.
Gather the Right Documentation
Your response has to include your Social Security number, the notice number from the upper right corner, and the tax year under examination. These identifiers connect your paperwork to the right file and prevent your response from disappearing into a processing backlog.5Internal Revenue Service. Understanding Your IRS Notice or Letter
What you send depends on what the IRS is questioning. Bank statements, canceled checks, and receipts form the backbone of most responses. For a receipt to hold up, it needs to show the amount, date, place, and essential nature of the expense. Travel and vehicle deductions require more: mileage logs with dates, destinations, and the business purpose of each trip. A round annual estimate will not satisfy the examiner. The agency wants contemporaneous records showing individual trips.6Internal Revenue Service. IRS Publication 463 – Travel, Gift, and Car Expenses
Match every document to the item the notice raises. If Letter 566 asks about charitable contributions, send the substantiation for those contributions, not a general packet about your whole return. Extra material invites extra questions.
How to Send Your Response
Send everything by certified mail with return receipt requested. Under the timely mailing rule, the postmark date counts as the date of delivery, which protects you if the IRS later claims your response arrived late. Certain designated private delivery services from FedEx and UPS also qualify.7Office of the Law Revision Counsel. 26 USC 7502 – Timely Mailing Treated as Timely Filing and Paying Keep copies of everything you send along with the mailing receipt.
Many recent audit notices include an access code for the IRS Document Upload Tool, which lets you submit documents electronically. The tool accepts JPEG, PNG, and PDF files up to 15 MB each, with a limit of 40 files per submission; PDFs are capped at 120 pages per file.8Internal Revenue Service. IRS Expands Secure Digital Correspondence for Taxpayers You can also use the tool without an access code by entering the notice number from your letter.9Internal Revenue Service. IRS Document Upload Tool
Agree, Disagree, or Ask for More Time
Every response falls into one of three categories.
If you agree with the proposed changes, sign the consent form that came with the notice and return it. The IRS will finalize the adjustment and send a bill for any additional tax, penalties, and interest.
If you disagree, write a clear explanation of why the changes are wrong and attach the documents that back your position. Vague disagreements without evidence go nowhere. The examiner needs to see the paper trail. If the notice is Letter 525, disagreement means filing a formal written protest within the 30 days and, if you want one, requesting a conference with the Office of Appeals.
If you need more time, call the number on the notice before the deadline. Do not send a partial response and assume the IRS will wait for the rest.
What Happens If You Don’t Respond
Ignoring an audit notice is the single worst move. The case does not go away. The examiner will adjust your return using the information the agency already has, which almost always means adding income and disallowing every deduction or credit under question. You then receive a Statutory Notice of Deficiency proposing a larger bill than you likely owed, plus penalties and interest.
If you still do not respond, the IRS assesses the tax and starts collection. That opens the door to federal tax liens, wage garnishment, and bank levies. You also lose the automatic right to an administrative appeal inside the IRS. Your remaining options are paying in full and suing for a refund, or asking for audit reconsideration with new evidence.
If the Audit Ends Against You: The 90-Day Letter
When you cannot reach agreement with the examiner and Appeals does not resolve the dispute, the IRS sends Letter 3219, a Statutory Notice of Deficiency. This is the most consequential document in the process. It formally proposes a tax deficiency and gives you exactly 90 days — 150 if you live outside the United States — to file a petition with the United States Tax Court. Tax Court is the only venue where you can challenge the proposed assessment without paying the disputed amount first.10Taxpayer Advocate Service. 90-Day Notice of Deficiency
The 90-day deadline cannot be extended by the IRS under any circumstances. Trying to negotiate during that window does not pause the clock. If the 90th day falls on a weekend or legal holiday, a petition is timely if filed the next business day. Miss the deadline and the IRS assesses the tax automatically; your only path afterward is to pay in full, file a refund claim, and sue in federal district court or the Court of Federal Claims.10Taxpayer Advocate Service. 90-Day Notice of Deficiency
Audit Reconsideration
If the examination closed because you missed the response deadline, or because the IRS assessed tax on a substitute return, you can request audit reconsideration. Reconsideration reopens a closed examination, but only when you have new documentation the IRS did not see the first time or can show a computational error. Submit the request in writing to the office that ran the original audit, with the supporting evidence. This is a last resort, not a routine appeal, and there is no guarantee the assessment will change.
Bringing in a Representative
You have the right to hire a representative at any point in the process. If the IRS contacts you for an interview and you say you want to consult with a representative, the employee must stop the interview. Your representative can then attend on your behalf, and the IRS generally cannot require you to appear alongside them unless a formal summons has been issued.11Internal Revenue Service. Taxpayer Representation
To authorize someone to handle the audit for you, file Form 2848, Power of Attorney and Declaration of Representative. Once it is on file, the IRS communicates with your representative instead of you.12Internal Revenue Service. Instructions for Form 2848, Power of Attorney and Declaration of Representative Attorneys, CPAs, and enrolled agents all have unlimited representation rights before the IRS. Enrolled agents specialize in federal tax and are licensed directly by the IRS; CPAs and attorneys have broader practices, and a tax attorney adds attorney-client privilege, which matters when a field audit raises the possibility of fraud allegations.
Fees vary. Tax attorneys typically charge $400 to $850 per hour for audit defense; CPAs generally run $200 to $500 per hour. A simple correspondence audit may take only a few hours; a contested field audit can run into tens of thousands of dollars.
If professional fees are out of reach, Low Income Taxpayer Clinics provide free or low-cost representation in audits, appeals, and collection disputes. You generally qualify if your income falls below a set threshold and the amount in dispute is under $50,000.13Internal Revenue Service. Low Income Taxpayer Clinics