A correspondence audit is handled entirely by mail. The IRS sends a letter asking for documentation of specific items, and you respond by mail or upload. A field audit is an in-person examination at your home, your place of business, an IRS office, or your representative's office. Correspondence audits are simpler, faster, and far more common.

What is a correspondence audit?

A correspondence audit starts and usually ends with letters. The IRS letter identifies the items on your return it wants to verify (often income, expenses, or itemized deductions) and gives you a deadline to respond. You gather the documents, mail them or upload them, and wait.

The IRS audits page notes one practical detail: if you have too many books or records to mail, you can request a face-to-face audit instead. The letter includes contact information and instructions. For letters with the contact numbers 866-897-0177 or 866-897-0161, you can also check your audit status in your individual online account under the Records and Status tab, where you see when the audit started, which letters were issued, and when your next response is due.

What is a field audit?

A field audit means an IRS examiner reviews your records in person. Per Publication 556, examinations not handled by mail can take place in your home, your place of business, an Internal Revenue office, or the office of your authorized representative. The IRS makes the final determination of when, where, and how the examination takes place, but if the scheduled time or place is not convenient, the examiner will try to work out something more suitable.

Field audits are broader and slower than correspondence audits. Instead of verifying two or three line items, the examiner looks through your books and records across the issues in scope, asks questions in real time, and can expand the examination if something looks off. This is where professional representation pays for itself: your representative handles the interview while you stay out of the room.

How do the two compare?

What do you need to provide in each?

Both types start from the same requirement: the IRS sends a written request for specific documents. The IRS audits page says the IRS accepts some electronic records in place of or in addition to paper ones, and you should confirm with your auditor what they accept. In a correspondence audit, that is the whole exchange. In a field audit, the document request is the starting point, followed by the interview, where you (or your representative) walk through the records and answer questions.

One rule applies to both: you must keep all records you used to prepare your return for at least three years from the filing date.

What if you need more time to respond?

Correspondence audit: fax your written extension request to the number on the letter (mail it if you cannot fax). The IRS can ordinarily grant a one-time automatic 30-day extension. If you received a Notice of Deficiency by certified mail, no extension is possible: you have 90 days to petition the U.S. Tax Court, and that deadline does not move.

Field audit: contact your assigned auditor to request more time. If needed, contact the auditor's manager. Do not just miss the date.

Source: IRS audits page.

What happens if you do not respond by the due date?

The IRS does not drop the audit. It completes the audit without your input and sends you an audit report with its proposed changes to your tax return. In practice, an audit where only the IRS talks to itself rarely ends in your favor. Responding on time is the single highest-leverage action in either format.

How does each audit end?

Both formats conclude the same three ways, per the IRS audits page:

• No change: you substantiated the items; nothing changes.

• Agreed: you understand and agree with the proposed changes; you sign the examination report and pay what you owe, plus interest.

• Disagreed: you understand but do not agree. You can request a conference with an IRS manager, use mediation (alternative dispute resolution), or file an appeal if enough time remains on the statute of limitations.

Publication 556 also reminds taxpayers that most agree with proposed changes and close the examination at that level, and that many examinations end in a refund or acceptance of the return without change.

Updated October 28, 2026.

This article is free educational content, not tax advice for your specific situation. If you want a plan built around your actual numbers, that is what our paid tax planning engagements do.