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How to fax an IRS audit response, Letter 525, 566, 915, and more

Fax your IRS audit response to the fax number printed on your audit letter (Letter 525, 566, 915, 3219, or other examination letter). The fax number routes to the specific examiner working your case, never use a generic IRS number for audit responses.

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Common IRS audit letters

LetterTypeResponse window
Letter 525 / 525-O30-day letter, preliminary report of audit changes30 days
Letter 566 / 566-SInitial audit notification, documentation request30 days
Letter 915Examination report with proposed changes30 days
Letter 95030-day letter for unagreed audit (appeal rights)30 days
Letter 3219Statutory Notice of Deficiency (90-day letter)90 days (Tax Court petition)
Letter 3501Field audit appointment letterDate specified

Finding the examiner's fax number

Every IRS audit letter has the examiner's fax number. Look in:

  • Upper right corner of page 1: Most audit letters include "Fax: [number]" near the contact info
  • Bottom of page 1 or 2: Some letters list contact info at the bottom
  • "How to Contact Us" section: Often includes both phone and fax

⚠️ Critical: Use ONLY the number on your specific letter. Audit responses sent to generic IRS fax lines do not reach your examiner, they are filed in a queue and may be discarded. Your timely-response protection is lost.

Critical deadlines

Missing an audit deadline has serious consequences:

  • Letter 525, 566, 915, 950: 30-day window. Missing means the IRS proceeds with the assessment as proposed.
  • Letter 3219 (Statutory Notice): 90-day window. After 90 days, you cannot petition Tax Court, your only option is to pay and sue for refund.
  • Document requests with specific deadlines: Missing means the IRS makes findings without your evidence.

Faxed = same-day delivery

Postal delays at the deadline can cost you appeal rights. Fax your audit response and get instant transmission proof.

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Preparing your audit response

A strong audit response includes:

  • Cover letter, addresses the examiner by name (from the letter), references the audit case number, summarizes your response position
  • Signed Form 2848 if a CPA/EA/attorney is responding on your behalf
  • Itemized response, for each issue the IRS raised, state your position and reference supporting documents
  • Supporting documents, receipts, contracts, bank statements, mileage logs, etc. Label each clearly (Exhibit A, Exhibit B, etc.)
  • Index/table of contents if response is more than 10 pages

Step-by-step: faxing the response

  1. Locate the examiner's fax number on your audit letter
  2. Compile cover letter, response, exhibits, and Form 2848 into a single PDF
  3. Number all pages (e.g., "Page 3 of 27")
  4. Add a cover sheet referencing the audit case number, examiner name, taxpayer name, SSN/EIN, and total page count
  5. Upload to Faxend.com/send, enter the examiner's fax number
  6. Pay $2.99 (or more for larger documents, Faxend handles up to 100+ pages)
  7. Save the transmission confirmation, this is your proof of timely response

What happens after you fax

The examiner reviews your response and either:

  • Accepts your position: Issues "no change" letter, audit closed.
  • Partially accepts: Issues revised exam report with adjusted amounts.
  • Rejects your position: Issues 30-day letter (if not already at that stage) or 90-day Statutory Notice.
  • Requests more info: Sends additional Information Document Request (IDR).

Response time varies by complexity: simple audits 30-60 days, complex audits 6-12 months.

Common mistakes

Faxing to a generic IRS number. Audit responses must reach the specific examiner. Use only the number on your letter.

Missing the deadline. Document deadlines are strict. Even one day late can forfeit appeal rights for 90-day letters.

Vague responses. "I disagree" without supporting documentation is dismissed. Be specific about each issue.

Sending originals. Always send copies, keep originals. The IRS does not return documents.

No table of contents. Long responses (20+ pages) without an index frustrate examiners and slow review.

Sources

Frequently asked questions

What is the IRS fax number for audit responses?
There is no universal IRS audit fax number. The fax number for your audit response is printed on your specific audit letter (Letter 525, 566, 915, 950, 3219, etc.), usually in the upper right corner of page 1. Always use the number on your letter.
How long do I have to respond to an IRS audit letter?
Most audit letters give 30 days. Letter 3219 (Statutory Notice of Deficiency) gives 90 days to petition Tax Court. Specific deadlines are printed on each letter, read carefully because the deadline is the date by which the IRS must RECEIVE your response, not the postmark date.
What happens if I miss an audit deadline?
For 30-day letters: the IRS proceeds with proposed assessments. For Letter 3219 (90-day letter): you lose the right to petition Tax Court, your only option becomes paying the assessment and suing for refund in district court. Missing deadlines is serious.
Should I respond to an IRS audit alone or with a CPA?
For complex audits, business audits, or large dollar amounts, hire a CPA, enrolled agent, or tax attorney. They communicate with the examiner directly via Form 2848. For simple audits with clear documentation (e.g., charitable deduction substantiation), you can respond yourself.
What documents should I include in my audit response?
Include: a cover letter addressing the examiner by name, a signed Form 2848 if represented, an itemized response addressing each IRS issue, supporting exhibits (clearly labeled), and a table of contents for long responses. Number every page.
Can I fax an audit response on a weekend?
Yes, IRS fax lines accept transmissions 24/7. The fax timestamp is your proof of timely response, the date the fax succeeded, not when the IRS opens it. Faxing Friday night before a Monday deadline counts as timely.
How long does the IRS take to process audit responses?
Simple audits: 30-60 days. Complex audits: 6-12 months or longer. The IRS may send additional Information Document Requests (IDRs) during review, which restart the response clock for those new items.
Can I appeal an IRS audit decision?
Yes. After receiving an unagreed audit determination (typically Letter 950 or similar), you can request an appeal with the IRS Office of Appeals. The Letter 950 explains your appeal rights and deadline. Faxing your appeal request is fastest.
What's the difference between Letter 525 and Letter 3219?
Letter 525 is a 30-day preliminary report, you can negotiate changes with the examiner. Letter 3219 is the Statutory Notice of Deficiency, formal IRS determination with 90 days to petition Tax Court. Letter 3219 is more serious; the deadline is jurisdictional.
Should I send originals or copies of my supporting documents?
Send copies only. The IRS does not return documents. If you fax originals, you may lose them permanently. Keep originals for your records and any subsequent litigation.
Can I request more time to respond to an audit?
Yes. Fax a written extension request to the examiner's number on your letter. Most examiners grant 30 additional days for reasonable requests. Request extensions BEFORE the original deadline, last-minute requests are more likely to be denied.
What if I receive a Letter 3219 after missing a 30-day letter?
You still have 90 days from Letter 3219 to petition Tax Court, even if you missed an earlier 30-day window. Don't ignore Letter 3219. Filing a Tax Court petition (Form 2) within 90 days preserves your right to dispute without paying first.

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