The IRS tax audit process is a structured review of specific items on your return, starting with a mailed notice and ending in one of three ways: no change, an agreed adjustment, or a disputed finding that you can appeal and, if necessary, take to court. Initial contact always comes by mail, never by phone or email, and you have defined rights and deadlines at every step.1Internal Revenue Service. IRS Audits What happens next depends on the type of audit, how well your records support what you filed, and whether you agree with the examiner’s conclusions.
The Three Types of Audits
The form your audit takes tells you a great deal about what to expect. The IRS runs three kinds, and the type usually reflects the complexity of what the agency wants to examine.
- Correspondence audit. The most common. The IRS mails you a letter asking for documentation to support specific items on your return, such as a deduction or a credit. You respond by mail or through a secure digital portal. There is no face-to-face meeting unless the issues grow more complex.
- Office audit. You bring your records to a local IRS office for an in-person interview with an examiner. These involve more detailed questions about income sources or deduction categories that cannot be resolved on paper alone.
- Field audit. An examiner comes to your home, place of business, or your representative’s office. Field audits are typically reserved for more complex returns, including those involving business income, multiple entities, or large-dollar discrepancies.
Whichever type you receive, the notice will identify the tax year at issue and the items the examiner wants to see. That list defines the scope of the audit. The IRS does have broad legal authority to examine books, papers, records, and other data when investigating any tax liability, so the scope can widen if the examiner finds reason to look further.2Office of the Law Revision Counsel. 26 USC 7602 – Examination of Books and Witnesses
What Documents the IRS Will Ask For
An audit is fundamentally a documentation exercise. The IRS wants proof that what you claimed on your return reflects real transactions. That means receipts, bank statements, canceled checks, invoices, and account records. If you claimed vehicle expenses or travel deductions, you will need a contemporaneous log showing dates, destinations, mileage, and business purpose.3Internal Revenue Service. What Kind of Records Should I Keep
Formal requests come on Form 4564, the Information Document Request (IDR). This form lists the specific items the examiner wants to review and sets a deadline for your response.4Internal Revenue Service. Internal Revenue Service Information Document Request Form 4564 Match your records to each numbered request on the IDR. That saves time and keeps the process focused. If you use accounting software, exporting transaction reports that align with the relevant line items on your return is usually the most efficient way to respond.
Your Rights During the Audit
Federal law gives you a specific set of protections known as the Taxpayer Bill of Rights. The IRS Commissioner is required by statute to make sure every agency employee knows and follows these ten rights, which include the right to be informed, the right to pay only the correct amount of tax, the right to challenge the agency’s position, the right to appeal, and the right to privacy and confidentiality.5Office of the Law Revision Counsel. 26 U.S. Code 7803 – Commissioner of Internal Revenue; Other Officials
The most practically important protection is the right to have a representative handle the audit for you. An attorney, certified public accountant, or enrolled agent with a signed power of attorney can attend interviews, respond to questions, and make legal arguments on your behalf. The IRS cannot force you to personally attend an interview alongside your representative. If you say at any point during an interview that you want to consult with a representative, the examiner is legally required to stop the interview immediately, even if you have already answered some questions.6Office of the Law Revision Counsel. 26 U.S. Code 7521 – Procedures Involving Taxpayer Interviews
How an Audit Ends
Every audit produces one of three outcomes.
A “no change” result means the examiner reviewed your return and accepted it as filed. You owe nothing additional and receive no penalties. This happens more often than people expect.
If the examiner proposes changes and you agree, you sign an examination report closing the case. The report calculates any additional tax, interest, and penalties. Once signed, the assessment is final and collection begins.
If you disagree, the examiner issues a 30-day letter. It explains the proposed adjustments, the reasoning behind them, and your options for challenging the result.7Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond You have 30 days from the date of the letter to file a written protest requesting a conference with the IRS Independent Office of Appeals.8Internal Revenue Service. Letters and Notices Offering an Appeal Opportunity
If You Disagree: Appeals and Beyond
Fast Track Settlement
Before going to formal Appeals, you may qualify for Fast Track Settlement, a voluntary mediation program. An independent mediator from the Appeals office works with you and the examiner to find common ground. The IRS aims to resolve these cases within 60 days for individuals and small businesses. Neither side can be forced to participate or accept a proposed agreement, and if mediation fails, you keep your right to pursue a traditional appeal.9Internal Revenue Service. Fast Track
The Appeals Conference
The Independent Office of Appeals is separate from the examination division. Appeals officers look at your case fresh, weigh the hazards of litigation for both sides, and try to settle. Most disputes that reach Appeals are resolved without a court filing. The process is less formal than court proceedings but still follows structured procedures, and any agreement reached at this stage is binding.
The 90-Day Letter and Tax Court
If Appeals does not resolve the case, or if you skip Appeals entirely, the IRS issues a Statutory Notice of Deficiency, commonly called the 90-day letter. It states exactly how much additional tax the IRS believes you owe and gives you a firm deadline to challenge it in court.
You have 90 days from the date the notice is mailed to file a petition with the United States Tax Court. If you are outside the country, the deadline extends to 150 days.10Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court Miss that deadline and the IRS assesses the tax automatically, with no further argument possible on the merits. This is one of the hardest deadlines in tax law, and it is not extended by filing a late return or by requesting more time from the IRS.
A petition can be filed electronically through the Tax Court’s DAWSON system or on paper by mail.11United States Tax Court. Guidance for Petitioners: Starting a Case The filing fee is $60. For disputes where the total amount at issue is $50,000 or less per tax year, the court offers a simplified small-case procedure that is faster and less formal than a regular trial.12United States Tax Court. Case Procedure Information The tradeoff: small-case decisions cannot be appealed by either side.
The key advantage of Tax Court is that you can challenge the proposed tax before paying it. If you pay first, you can file a refund claim and then sue in federal district court or the Court of Federal Claims, but most individual taxpayers prefer not to write the check before their day in court.
Penalties and Interest If You Owe
When an audit finds that you owe more tax, penalties and interest often follow. The amounts can be significant enough that the penalty itself becomes the main financial hit.
Accuracy-Related Penalty
If an underpayment is due to negligence or a substantial understatement of income tax, the IRS adds a penalty equal to 20% of the underpaid amount.13Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments A “substantial understatement” for individuals means your tax was understated by the greater of 10% of the correct tax or $5,000. If you claimed a qualified business income deduction under Section 199A, that 10% threshold drops to 5%.
Civil Fraud Penalty
If the IRS proves that part of your underpayment was due to fraud, the penalty jumps to 75% of the portion attributable to fraud.14Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty The burden of proof for fraud falls on the IRS, which must show its case by clear and convincing evidence. The agency cannot stack a fraud penalty and an accuracy penalty on the same dollars; it picks one or the other.
Interest on Underpayments
Interest accrues on any unpaid tax from the original due date of the return until the balance is paid. The IRS sets the rate quarterly based on the federal short-term rate plus three percentage points. For the first quarter of 2026, the rate for individual underpayments is 7%; for the second quarter, it drops to 6%.15Internal Revenue Service. Quarterly Interest Rates Interest is not negotiable. It runs automatically and compounds daily.
What Happens If You Ignore the Notice
Not responding is one of the most expensive mistakes you can make. If you miss the deadline in the IRS letter, the agency completes the audit without your input and sends a report with its proposed changes.1Internal Revenue Service. IRS Audits Those changes will almost always be worse than what cooperation would have produced, because the examiner has no documentation from you to reduce any adjustments. The 30-day and 90-day letters still follow. Once the 90-day window closes without a Tax Court petition, the assessment becomes final and the IRS moves into collection.
How Far Back the IRS Can Go
The IRS cannot come after you indefinitely. Under the general rule, the agency has three years from the date you filed your return to assess additional tax.16Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection If you filed early, the clock starts on the due date of the return, including extensions. This deadline is called the Assessment Statute Expiration Date.
Several situations stretch or eliminate the three-year window:
- If you left out more than 25% of the gross income shown on your return, the IRS gets six years.16Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection
- If you filed a return with the intent to evade tax, there is no time limit at all.17Internal Revenue Service. Time IRS Can Assess Tax
- If you never filed a required return, the statute of limitations never starts running.17Internal Revenue Service. Time IRS Can Assess Tax
- The IRS may ask you to sign a statutory waiver extending the assessment period. You are not required to agree, but refusing may cause the examiner to make a determination using only the information already available.
The statute is also suspended while a notice of deficiency is outstanding and during bankruptcy proceedings. Because of those extensions, your record retention should track the assessment window. Three years is the baseline for taxpayers who filed accurately and reported all income; six years covers the extended window if income was substantially understated; and records should be kept indefinitely for any year in which you did not file or filed a fraudulent return.18Internal Revenue Service. How Long Should I Keep Records When in doubt, six years covers most extended-audit scenarios, and the cost of storing digital copies is trivial compared to losing a deduction because the receipt is gone.