First: use the fax number on your letter
If you’re answering an IRS notice or letter, the right fax number is printed on it. Numbers differ by notice and by processing center, so a number from a website (including this one) can be the wrong one for your letter. For a CP05A notice, for example, the IRS says to fax “to the fax number in the notice using either a fax machine or an online fax service”, and that your reply must include a copy of the notice.
Step by step
- Tap New Fax and scan the pages: the notice (or its response form), then your documents. Crop and reorder them so the notice comes first.
- Type the fax number exactly as printed on the notice or form. US numbers work without +1.
- Add a free cover page with the notice or form number (such as “CP2501” or “Form 2848”), your name and a phone number. Leave your Social Security number off the cover page: whoever picks up the fax sees it first.
- Tap Send and wait for Delivered: it means the IRS fax machine confirmed every page.
- Open the fax and share the receipt to Files. The IRS doesn’t confirm receipt for some notices, so keep the receipt with the time and page count.
Signatures: when your drawn signature isn’t enough
For Forms 2848 and 8821, the IRS requires a handwritten ink signature on forms sent by fax: “Digital, electronic, or typed-font signatures are not valid signatures for Forms 2848 filed by mail or by fax.” So don’t use FaxBuddy’s signing tool for these two forms. Print the form, sign it with a pen, then scan it with FaxBuddy. (Forms with electronic signatures can be submitted online at IRS.gov/Submit2848 instead.)
For other forms and notice replies, follow what the form or notice asks for.
Common IRS fax numbers
From irs.gov, checked 22 October 2026. The IRS says these numbers can change without notice; check the linked page before you send.
| What you’re sending | Fax number |
|---|---|
| Form SS-4, EIN application (business or residence in the 50 states or D.C.) | 855-641-6935 |
| Form SS-4, no residence or business in any state, faxing from the US / from abroad | 855-215-1627 / 304-707-9471 |
| Forms 2848 and 8821, eastern states (Memphis) | 855-214-7519 |
| Forms 2848 and 8821, western states (Ogden) | 855-214-7522 |
| Forms 2848 and 8821, territories, APO/FPO, abroad | 855-772-3156, or 304-707-9785 from outside the US |
| Form 4506-T, individual transcripts | 855-587-9604 (Austin), 855-821-0094 (Kansas City) or 855-298-1145 (Ogden), by the state you lived in |
| Form 8802, US residency certification | 877-824-9110 (from the US) or 304-707-9792 |
Which states go to Memphis or Ogden, and to which 4506-T office, is listed in each form’s instructions: SS-4, 2848, 8821, 4506-T, 8802.
Good to know
- Send it one way only. Faxing and also mailing the same reply can slow it down. On its CP142 page, for example, the IRS asks you to send your response using only one method.
- EIN by fax: the IRS faxes the EIN back, generally within 4 business days, to the fax number you give on the form. FaxBuddy sends only, so for a reply by fax you’ll need a fax number elsewhere; US applicants can also apply for an EIN online.
- Some forms can’t be faxed. Form 4506 (a copy of a return) and Form 8822 (change of address) go by mail.
- Up to 50 pages per fax in FaxBuddy. For a longer reply, send it in parts and say so on each cover page (“part 1 of 2”).
- Privacy: the IRS asks you to understand your fax service’s privacy policy. FaxBuddy sends your pages encrypted to our servers in the EU and deletes them from our servers and our fax provider within 24 hours after the fax is delivered or fails. The last stretch over the phone network is an ordinary fax, as from any fax machine. Privacy Policy
FaxBuddy isn’t affiliated with the IRS, and this isn’t tax advice. Fax numbers and quotes from irs.gov, checked 22 October 2026.
Questions
Can I fax the IRS from my iPhone?
Yes. The IRS accepts replies to many notices by fax and says an online fax service is fine. Scan the pages in FaxBuddy, type the fax number printed on your notice, and send.
What fax number do I use to reply to an IRS notice?
The one printed on your notice or its response form. Numbers differ by notice and processing center.
Can I sign Form 2848 or 8821 in the app?
Not for faxing. The IRS requires a handwritten ink signature on faxed Forms 2848 and 8821. Sign the printed form with a pen, then scan it.
How do I know the IRS got my fax?
FaxBuddy shows Delivered when the IRS fax machine confirms every page, and gives you a receipt with the time and page count. Keep it: the IRS doesn’t confirm receipt for some notices.
What does it cost to fax the IRS?
One credit per page, from $0.40 a page. Your first page is free, the cover page is free, and if the fax doesn’t go through, the credits come back.