A correspondence audit is an examination the IRS runs entirely by mail from one of its campuses — no office visit, no agent at your door. It usually covers a single tax year and one or a few issues: a credit you claimed, a deduction, a mismatch between your return and a form the IRS received. Publication 3498-A is the IRS’s own rules sheet for these exams, and most of what decides your case is simpler than the envelope suggests: the right documents, sent the right way, before the deadline.
General information, not tax or legal advice. If your letter alleges fraud or unreported business income, or the amounts are large, consult a tax professional before responding.
Correspondence exams are automated and single-issue by design. Your case is not assigned to one examiner who follows it end to end: the Taxpayer Advocate Service’s central finding on these audits is that no single employee owns your case — your letters go into a campus workstream, and your calls reach a toll-free assistor pool of employees who pick the file up fresh. That one fact explains the experience everyone reports: repeat requests for documents you already sent, long gaps, and letters that seem not to have read your last letter. The defence is paperwork discipline — the reply cover sheet on every submission, copies of everything, and proof of delivery (the letter itself, written to survive being read by a stranger, is a separate craft: how to respond to an IRS audit letter).
Two opening styles exist in campus practice: a plain initial contact letter (audit notice, no balance proposed — used on all EITC exams) and a combo letter (notice and examination report together, where the IRS is already reasonably certain of the adjustment). With a combo letter your first letter is the decision letter — treat its deadline accordingly.
On every channel, the same rules from the IRS’s “Audits by mail” guidance apply: always include the reply cover sheet that came with your letter, and send copies, never originals — originals sent to a campus can be lost, and you will need the records again if the case continues.
You can get it — but ask first. Fax a written extension request to the number on your letter (or mail it) before the deadline, saying what you are gathering and when you will send it. A request made after the date passes arrives in a case that may already have moved to the next letter.
Assembling documents that actually prove each item: the record-keeping checklist. The whole audit map: IRS audit help.
How does an IRS audit by mail work? The IRS campus writes to say your return was selected, names the items questioned and the documents to send, and you substantiate them by upload, fax or mail. If your documents support the return, the audit closes with no change; if not, the IRS proposes adjustments on Form 4549 and the case proceeds through the 30-day letter toward Appeals or a Notice of Deficiency (the IRS’s “Audits by mail” guidance describes the same sequence).
Can I upload my documents instead of mailing them? Yes. The IRS Document Upload Tool (irs.gov/examreply, or the link/QR code on your letter) accepts exam documents, and the IRS lists upload, fax and mail as the three response channels. Include the reply cover sheet either way, and keep copies of everything you send.
What happens if I don’t respond to a correspondence audit? The case advances without you. TAS describes roughly 165 days from the first letter through two ~30-day response letters to the Statutory Notice of Deficiency, after which the IRS assesses the proposed tax, penalties and interest. Your remaining remedies narrow to a Tax Court petition (within the 90-day window) or, after assessment, audit reconsideration with documents the examiner never saw.
Will one examiner handle my mail audit? No — and that is by design, not by accident. TAS’s correspondence-audit research found no single assigned examiner owns these cases end to end; letters and calls are handled by a campus workstream and a toll-free assistor pool. Write every response as if the reader has never seen your file: identify your case on the cover sheet and reference what you sent before.
Sources: IRS.gov — “IRS audits,” “Audits by mail: What to do,” “IRS Update on Audits”; IRS Publications 3498-A and 3498 (Rev. 5-2025); Taxpayer Advocate Service, Most Serious Problems on correspondence examinations (Annual Reports to Congress). Currency verified 2026-10-23.