How to Fax the IRS in 2025: Numbers, Forms, and Best Practices

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.

Important update: International CAF Team fax (Form 2848)

For Power of Attorney submissions on Form 2848 sent from outside the United States to the IRS International CAF Team, the fax number changed to +1 (267) 466‑1017. The previous +1 (267) 941‑1017 is no longer in service. If sending from within the U.S., the domestic fax remains +1 (855) 772‑3156. Source: IRS Instructions for Form 2848 (Rev. December 2015) — see “The International CAF Team Fax Number for Filing Form 2848 Has Changed.”

IRS Instructions for Form 2848 (Rev. 2015)

Notes:

• This update applies specifically to Form 2848 filings to the International CAF Team, not to other IRS correspondence or units.
• IRS fax numbers can change without notice; always verify the current number on your notice or in the latest Form 2848 instructions before sending.

How to Format Your Fax to the IRS

1. Prepare a clear PDF (preferred). Avoid photos of documents when possible
2. Include a cover sheet with: name, SSN/TIN (last 4 digits), notice/letter number, tax year, phone, and page count
3. Put the notice or letter first, followed by your response and supporting docs
4. Use black text on white background; ensure signatures are dark and readable
5. 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

Which IRS Forms Are Commonly Faxed?

• 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.