How to Fax IRS Form SS-4 to the IRS — EIN Application
Form SS-4 is how a new business, estate, trust, or nonprofit applies for an Employer Identification Number. The fax-in route is a long-standing IRS process: if you supply a return fax number, the IRS faxes the assigned EIN back to you in roughly four business days, which is why many applicants who cannot use the online tool choose fax. This guide covers preparing a complete SS-4, sending it to the correct service center, and receiving the EIN back.
Does the IRS accept a fax?
Yes — the fax-in method is described in the Instructions for Form SS-4, and it is one of the primary ways domestic applicants request an EIN when the online application does not fit their situation. Provide your own return fax number and the IRS faxes the EIN back after processing, typically within about four business days.
Finding the official fax number
The correct destination depends on where the business is located, and the current fax number for domestic applicants is listed in the Instructions for Form SS-4 under the 'Where To File or Fax' table. International applicants use a different line. Read that table in the latest instructions each time, since the IRS updates the service-center assignments.
What to include on every page
- The legal name of the entity and any trade name exactly as it will be used
- The responsible party's name and SSN, ITIN, or EIN as required on line 7b
- The reason for applying, entity type, and expected first wages or start date
- A working return fax number so the IRS can fax the assigned EIN back to you
- The signature, title, and daytime phone of the authorized person on the form
How to fax IRS Form SS-4 (Application for Employer Identification Number) to the IRS
- 1Complete every required line of Form SS-4, including the responsible party and entity type
- 2Confirm the return fax number you list is one you actively monitor for the EIN reply
- 3Look up the current domestic fax destination in the Instructions for Form SS-4 'Where To File or Fax' table
- 4Scan or export the signed SS-4 as a clear single PDF
- 5Log in to Send FAX Mail, upload the PDF, enter the verified IRS fax number, and send
- 6Watch for the IRS fax reply with the assigned EIN, usually in about four business days
Confirming it arrived
Send FAX Mail gives you a dated confirmation the instant the SS-4 reaches the IRS fax line, so you know exactly when the application was submitted. The IRS then faxes the EIN back to the return number you listed, generally within about four business days — if nothing arrives in that window, re-verify the destination and the return number before resending.
What’s current · as of July 2026
Recent updates
Federal agencies still write fax into new rules and notices
The Federal Register — the daily journal of U.S. federal rulemaking — regularly publishes rules and notices that reference fax as an accepted or required submission channel for filings with agencies like the IRS, SSA, and CMS. That is why fax remains a live requirement for many official forms even as electronic portals expand.
Federal Register →
Faxing IRS Form SS-4 (Application for Employer Identification Number) to the IRS — FAQ
That is the design of the fax-in method: list a return fax number you can access, and the IRS faxes the assigned EIN to it once the application clears, usually inside four business days. Without a return number, they mail the number instead, which takes considerably longer.
No. The online assistant works for many applicants, but faxing SS-4 remains a valid path — and it is the route to take when the responsible party lacks an SSN or ITIN that the online tool requires, or when you prefer a paper trail. Both produce the same EIN.
The 'Where To File or Fax' table in the current SS-4 instructions maps domestic applicants to a specific fax line by state; international filers use a separate one. Pull that table fresh before sending, because the assigned center can change between form revisions.
Incomplete responsible-party details on line 7, a missing signature, or an unreadable return fax number are the common causes of delay or a follow-up letter. Double-check line 7 and confirm your return number is legible so the reply reaches you within the usual window.
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