An EIN is the tax identifier a business needs before it can open a bank account, hire anyone, or file a return. The fastest route is the IRS online application, which issues one immediately. But the online route is not open to everyone — and when it is closed to you, fax is the practical alternative, returning an EIN in about four business days.
This guide covers the verified numbers to fax Form SS-4, what to put on it so the IRS can return your EIN quickly, and how the fax route compares to the alternatives.
Table of Contents
- Fax numbers for Form SS-4
- When fax is the right route
- Getting the form right
- What happens after you send it
- Frequently asked questions
Fax numbers for Form SS-4
From the IRS instructions for Form SS-4, checked August 2026.
| Applicant | Fax number |
|---|---|
| Legal residence or principal place of business in one of the 50 states or DC | 855-641-6935 |
| No legal residence or principal place of business in any state, applying from within the US | 855-215-1627 |
| Applying from outside the United States | 304-707-9471 |
The fax-TIN service operates 24 hours a day, seven days a week. The IRS notes that long-distance charges may apply to the non-toll-free number.
When fax is the right route
The online EIN application is faster — it issues the number at the end of the session. Use it if you can.
Fax becomes the route in a few specific situations:
- The responsible party has no SSN or ITIN. The online application requires one; the fax route does not, which is why foreign-owned entities frequently end up here.
- The online session keeps failing. The application has to be completed in one sitting and times out; some applicants simply cannot get through it.
- You need a paper trail. A faxed submission with a transmission confirmation documents exactly when you applied, which occasionally matters for entity formation timelines.
- You are applying on someone's behalf in a way the online flow does not accommodate.
International applicants have a fourth option worth knowing: the IRS issues EINs by phone to foreign applicants, which usually beats a fax round trip across time zones.
Getting the form right
Two fields decide how smoothly this goes.
The responsible party. This is the individual who controls or manages the entity — a real person, with their SSN, ITIN, or EIN. Getting this wrong or leaving it vague is the most common reason an SS-4 comes back for clarification. The IRS wants a person, not a holding company.
Your return fax number. This is where the IRS sends your EIN. Omit it and the assignment notice goes by mail, turning four business days into several weeks. Double-check the digits — this is the number a stranger's machine receives your EIN at if you mistype it.
Beyond those: complete every line, state the reason for applying accurately, and make sure the legal name matches your formation documents exactly. A name that differs from your articles of organisation creates problems later when a bank compares the EIN letter to your paperwork.
What happens after you send it
The IRS generally returns the EIN by fax within four business days.
Keep both documents: your transmission confirmation, and the EIN assignment notice the IRS faxes back. The assignment notice is what banks, payroll providers, and state agencies ask for. It is also genuinely hard to replace — the IRS will confirm an existing EIN by phone, but re-issuing the original notice is not something they do casually.
If you are opening a business bank account next, faxing documents to a bank covers what they typically want and how to send it. If you will be authorising an accountant to deal with the IRS on the entity's behalf, that is Form 2848.
For the full list of what the IRS accepts by fax, see faxing documents to the IRS. No fax machine required — sending it online is $2.99 with no subscription, and the delivery confirmation lands in your inbox.
Frequently asked questions
What is the fax number for Form SS-4?
855-641-6935 if your legal residence or principal place of business is in one of the 50 states or the District of Columbia. If it is not, use 855-215-1627 from inside the United States, or 304-707-9471 from outside it.
How long does it take to get an EIN by fax?
The IRS guidance says you can generally receive your EIN by fax within four business days. The fax line accepts submissions 24 hours a day, seven days a week.
Should I apply online instead of faxing?
If you can, yes — the online application issues an EIN immediately. Fax is the route when the online application is unavailable to you, which includes applicants whose responsible party has no SSN or ITIN, and cases where the online session keeps failing.
Do I need to include a return fax number on Form SS-4?
You should. The IRS sends the EIN back by fax to the number you provide. Without one, the assignment notice goes by mail instead, which takes considerably longer.
Can I fax Form SS-4 from outside the United States?
Yes, to 304-707-9471. International applicants can also obtain an EIN by phone, which is often faster than waiting for a fax round trip across time zones.