An IRS audit usually takes anywhere from a few months to more than a year, and the range is that wide because there are three different kinds of audits. A mail-based correspondence audit often closes in three to six months. An in-person office audit runs about the same, sometimes a little longer. A field audit, where an IRS revenue agent examines your records at your home, business, or accountant’s office, commonly stretches to a year and can go longer for complex returns.1Internal Revenue Service. IRS Audits So the honest answer to how long does an IRS audit take is: it depends on which type the IRS opens, how complicated the issues are, and how quickly you send in what the auditor asks for.
Audits are also uncommon. In fiscal year 2024, the IRS audited about 0.19% of returns processed. For most filers, the question never comes up. If it does, the timeline below is what to expect.
How Long Each Type of Audit Takes
Correspondence Audits
These are the most common and the least invasive. The IRS mails a letter asking for documentation on one or two specific items on your return, such as a charitable deduction or an education credit. You send the records back, an examiner reviews them, and the case closes. Most correspondence audits wrap up within three to six months when you respond promptly. Slow responses are the single biggest reason these drag on.
Office Audits
An office audit brings you into an IRS office for an in-person interview with your records. The scope is broader than a correspondence audit but still limited. Three to six months is typical, though returns with business income or rental properties can push longer.
Field Audits
Field audits are the most thorough. A revenue agent visits your home, business, or accountant’s office and examines your return in detail.1Internal Revenue Service. IRS Audits These are reserved for more complex situations, including self-employment income, larger businesses, or returns with significant deductions. Plan on a year, and know that complicated cases can stretch beyond that.
When the IRS Can Start an Audit
The IRS can’t reach back forever. Under federal law, the standard window to assess additional tax is three years from the date you filed the return. If you filed early, the clock starts on the due date. A return due April 15 but submitted March 1 is treated as filed on April 15.2Office of the Law Revision Counsel. 26 U.S. Code 6501 – Limitations on Assessment and Collection
Two situations stretch that window:
- If you omit gross income exceeding 25% of what you reported, the IRS gets six years.2Office of the Law Revision Counsel. 26 U.S. Code 6501 – Limitations on Assessment and Collection
- If the return is fraudulent or you never filed at all, there is no time limit. The IRS can come after you decades later.2Office of the Law Revision Counsel. 26 U.S. Code 6501 – Limitations on Assessment and Collection
Practically speaking, most audits start within the first two years after you file, because the IRS needs time to complete the work before the three-year clock runs out. Once three full years pass with no contact, that return is generally safe.
What Speeds Up or Slows Down Your Audit
The single biggest factor within your control is how quickly and completely you respond. Auditors juggle dozens of cases at once. Send organized, clearly labeled records within a week of the request and your case moves. Wait until the last day of every deadline and mail an unsorted pile, and you’re looking at months of back-and-forth.
The IRS will send a specific list of records it needs, and the request should never require you to create something that doesn’t already exist.3Internal Revenue Service. Audits Records Request Send copies, never originals. If a document is missing, contact the bank, employer, or issuer for a replacement. Gaps are where adjustments happen; the IRS isn’t required to take your word for a deduction you can’t prove.
Complexity also matters. Wage income takes far less time to verify than partnership distributions, rental real estate, or foreign accounts. And some delays are outside your control entirely: an auditor’s caseload, IRS staffing, and the difficulty of the issues can all add weeks or months that have nothing to do with what you sent in.
When the IRS Asks to Extend the Deadline
Occasionally an audit is still open as the three-year assessment window nears its end. When that happens, the IRS asks you to sign Form 872, which extends the assessment period to a specific future date. Signing is voluntary. The IRS is legally required to tell you, each time it makes this request, that you can refuse, limit the extension to specific issues, or propose a shorter period.4Internal Revenue Service. 25.6.22 Extension of Assessment Statute of Limitations by Consent
Refusing doesn’t end the audit. If you decline, the IRS will likely issue a statutory notice of deficiency based on whatever information it has, which may not favor you. Agreeing to a reasonable extension often buys you time to present your side. If an auditor seems to be dragging things out, a shorter or issue-limited extension is the middle path.
What Happens When the Audit Ends
Every audit closes one of three ways:5Internal Revenue Service. 4.46.5 Resolving the Examination
- No change. The IRS accepts your return as filed.
- Agreed. You accept the proposed adjustments, sign, and pay any additional tax, interest, and penalties.
- Unagreed. You disagree, and your appeal rights kick in.
If you disagree, the IRS sends a letter explaining the changes and your right to appeal. You generally have 30 days from that letter to file a written protest requesting a hearing with the IRS Independent Office of Appeals.6Internal Revenue Service. Preparing a Request for Appeals Appeals can add months to the overall timeline, sometimes longer, depending on how quickly the office picks up the case.
If Appeals doesn’t resolve it, or you skip that step, the IRS issues a Notice of Deficiency, often called a 90-day letter. You have 90 days from the date of that notice to file a petition with the U.S. Tax Court. Taxpayers outside the country get 150 days.7Internal Revenue Service. Understanding Your CP3219N Notice Missing that deadline is a serious mistake. Once the 90 days pass, the IRS assesses the tax and your options narrow sharply.
Audit Reconsideration
If tax was assessed and you later find documentation you didn’t have during the audit, you can request an audit reconsideration. You must have filed the return in question, the assessment must remain unpaid or involve a reversed credit you’re disputing, and you must bring information the IRS didn’t consider originally.8Internal Revenue Service. 4.13.1 Examination Audit Reconsideration Process Reconsideration requires genuinely new evidence or proof of a computational error, not a second run at the same arguments.
A CP2000 Notice Is Not an Audit
Many taxpayers receive a CP2000 notice and assume they’re being audited. It isn’t an audit. It’s an automated letter generated when the income and payments reported on your return don’t match the W-2s, 1099s, and other documents filed under your Social Security number. You can usually resolve it by responding with documentation or agreeing to the proposed adjustment. If you ignore it, the IRS will assess the additional tax and send a bill.9Internal Revenue Service. Understanding Your CP2000 Series Notice The response window is much shorter than an audit’s full timeline, and the fastest way to close one out is to answer promptly with the paperwork the notice asks for.