How Long Does an IRS Audit Take?

Quick Answer

An IRS audit typically takes 3 to 12 months from start to finish. Simple correspondence (mail) audits often resolve in 3–6 months, while office and field audits involving businesses or complex returns can stretch to a year or longer. The timeline depends on the audit type, the issues involved, and how quickly you respond.

Audit Duration by Type

The IRS conducts three main types of audits, each with a different scope and timeline.

Audit Type	Typical Duration	What It Involves
Correspondence (mail)	3–6 months	Handled by mail; specific line items
Office audit	3–9 months	In-person at an IRS office
Field audit	6–18 months	Agent visits home or business
Complex business audit	1–3 years	Multiple years or entities

How Far Back Can the IRS Go?

Generally, the IRS audits returns filed within the last 3 years. If it finds a substantial error (understating income by 25% or more), it can go back 6 years. There's no time limit for fraudulent or unfiled returns. Note that the statute of limitations to assess additional tax is usually 3 years from the filing date, which shapes how audits are scheduled.

Factors That Affect How Long It Takes

• Audit type and complexity: More issues and more tax years mean a longer process.
• Your responsiveness: Providing requested documents promptly is the biggest lever you control.
• Availability of records: Missing receipts or statements cause back-and-forth.
• Agreement vs. dispute: Accepting the findings ends it quickly; disagreeing adds appeals.
• IRS workload: Staffing and seasonal backlogs affect scheduling.

Steps in the Audit Process

1. You receive an IRS notice by mail (the IRS never initiates an audit by phone or email).
2. You gather and submit the requested documentation.
3. The examiner reviews records and may ask follow-up questions.
4. The IRS issues its findings (no change, a refund, or additional tax owed).
5. You agree, or you request an appeal or additional review.

How to Speed Up (and Survive) an Audit

• Respond by every deadline in the notice; ask for an extension in writing if you need one.
• Send organized, clearly labeled copies — never originals.
• Answer only what's asked; don't volunteer extra tax years.
• Consider hiring a CPA, enrolled agent, or tax attorney for office or field audits.
• Keep a written log of all correspondence and dates.

If You Disagree With the Results

You can request a conference with the examiner's manager or appeal to the IRS Office of Appeals, which can add several months. If still unresolved, you may petition the U.S. Tax Court. Beware of scams: a real audit always starts with a mailed letter, never a threatening phone call demanding immediate payment.