An IRS audit can take anywhere from three months to three years, depending on the type. The largest variable is not how complex your return is — it’s which type of audit the IRS opened. Here is what to expect at each stage and where the real time gets spent.
The Short Answer by Audit Type
- Correspondence audit: typically 3 to 6 months from first notice to closing letter.
- Office audit: typically 6 to 12 months from initial appointment to closing.
- Field audit: typically 1 to 2 years, sometimes longer for businesses with multi-year examinations.
- CP2000 (Automated Underreporter): typically 60 to 90 days if you respond promptly with documentation.
- Appeals (if you protest): add another 6 to 18 months on top of the audit timeline.
- Tax Court (if you petition): add 12 to 24 months, often longer.
The IRS’s Internal Clock: The Statute of Limitations
The IRS has three years from the date you filed your return to assess additional tax. That window is six years if the omitted income exceeds 25% of gross income reported, and it’s unlimited for civil fraud or returns that were never filed. This is the IRS’s deadline, and it drives much of the audit’s tempo.
When the three-year clock is about to expire, examiners often ask you to sign a Form 872 to extend the statute. You don’t have to sign — but if you refuse, the IRS may issue a Statutory Notice of Deficiency immediately rather than continuing to work the case. Whether to sign is a strategic decision that depends on the strength of your position and how much work the examiner has left.
Stage-by-Stage Timeline
Weeks 1–2: The Notice and Your First Response
The notice arrives with a 30-day response deadline. During this window you should pull transcripts, gather documents, and decide on representation. If you need more time, request an extension in writing before day 30.
Weeks 3–8: Initial Document Exchange
The IRS reviews your response. For a correspondence audit, this is most of the case. For office or field audits, the examiner will issue additional IDRs as they work through the records.
Months 3–9: Field Work and Examiner Analysis
For office and field audits, the examiner conducts interviews, reviews source documents, may issue summonses to third parties (banks, vendors), and applies indirect methods like bank-deposit analysis or net-worth analysis where records are incomplete. This is usually the longest stage.
Months 9–12: Proposed Adjustments and Closing
The examiner issues a Form 4549 or revenue agent report. You agree, partially agree, or disagree. If you agree, the audit closes within a few weeks. If you disagree, the 30-day letter starts the Appeals clock.
Months 12–30: Appeals
Appeals conferences are scheduled 4 to 12 months after the protest is filed, depending on the office. Most Appeals cases settle within 18 months of being docketed. About 80% of cases sent to Appeals settle there.
Months 24+: Tax Court (If You Petition)
If the case doesn’t settle at Appeals and you petition the Tax Court, expect another 12 to 24 months for trial preparation, discovery, and decision — often more for complex cases.
What Speeds an Audit Up
Three things shorten an audit. Responding to the first IDR completely and on time keeps the examiner from sending follow-up requests. Being organized — documents indexed, bank deposits reconciled, mileage logs ready — lets the examiner finish faster. And conceding clearly losing issues early lets the case focus on what’s actually in dispute.
What Drags an Audit Out
Missing deadlines, sending partial responses that trigger follow-up IDRs, refusing to extend the statute (which can force the IRS to issue a notice of deficiency before the case is fully worked, sometimes to your detriment), and litigating issues that are factually weak. Any of those can add six to twelve months — or more.
Don’t Wait Until the Deadline
Every deadline in an audit is leverage. Win Your IRS Audit shows you how to use the calendar in your favor — statute extensions, response timing, when to ask for delay and when to push forward.