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Faxing the IRS is still common for responses to notices, identity verification, transcripts, and urgent follow‑ups. Here’s how to do it right the first time.
IRS Fax Numbers: Where to Send
IRS fax numbers change by form and department. Always verify the destination shown on your specific notice or instruction sheet. Common destinations include:
- Notice responses (CP/Letter series): The top-right of the notice lists a fax number
- Identity Verification (5071C/6331C): Use the number on your letter
- Taxpayer Advocate Service: +1 (855) 297‑0055
- International taxpayer assistance: +1 (267) 941‑1055
If you don’t have a number on your notice, call the IRS at 800‑829‑1040 to confirm before sending.
- Prepare a clear PDF (preferred). Avoid photos of documents when possible
- Include a cover sheet with: name, SSN/TIN (last 4 digits), notice/letter number, tax year, phone, and page count
- Put the notice or letter first, followed by your response and supporting docs
- Use black text on white background; ensure signatures are dark and readable
- Send during IRS business hours for faster handling
Learn the fundamentals first in our guide: How to Send a Fax Online
Sample IRS Fax Cover Sheet
[YOUR NAME]
[ADDRESS]
[PHONE] [EMAIL]
TO: Internal Revenue Service — [Department]
FAX: [Fax Number from Your Notice]
DATE: [MM/DD/YYYY]
PAGES: [Total pages incl. cover]
RE: [Notice/Letter Number], Tax Year [YYYY], SSN/TIN (last 4): [____]
Notes: [Brief description of enclosed documents]
For a full legal cover sheet template, see: Fax Cover Sheet Templates
- Identity verification responses (5071C/6331C letters)
- Audit responses and correspondence exams
- Installment agreement requests and supporting docs
- POA authorizations (Form 2848) when instructed
- Reasonable cause statements and penalty abatement support
When in doubt, follow the instructions on your letter; not all forms are accepted by fax.
Security and Compliance
- Use an encrypted online fax service
- Only include the last 4 digits of SSN on the cover sheet
- Remove unrelated pages to minimize exposure
- Save the transmission confirmation for your records
Read more: Fax vs Email Security and How Secure Are Faxes?
Troubleshooting Failed IRS Faxes
- Busy signal: Try again during off-peak hours
- Poor quality: Export to PDF and rescan at 300 DPI
- Wrong number: Confirm with your notice or call the IRS
- Missing pages: Re-send with page numbers (1/5, 2/5, …)
If timing is critical, send by fax and mail a hard copy via certified mail for redundancy.