How to fax Form SS-4 to the IRS from your phone
Form SS-4 is the application for an Employer Identification Number (EIN). You can send it to the IRS by fax and get the EIN faxed back, usually within four business days. Here is how to do it from an iPhone, with the numbers taken from the IRS's own instructions.
Before you fax: if your business is in the United States or a U.S. territory, the IRS recommends applying online at IRS.gov/EIN. The online application gives you the EIN right away and costs nothing. Fax makes sense when you can't use the online tool, or when someone else (an accountant, a lawyer) is applying for you.
The SS-4 fax numbers
These come from the Instructions for Form SS-4 (Rev. December 2025), checked on irs.gov on October 16, 2026. The IRS says the numbers may change without notice, so open the current instructions on the day you send.
| Where your business is | Fax Form SS-4 to |
|---|---|
| One of the 50 states or the District of Columbia | 855-641-6935 |
| No legal residence or office in any state or DC, faxing from inside the U.S. | 855-215-1627 |
| No legal residence or office in any state or DC, faxing from outside the U.S. | 304-707-9471 |
The IRS calls this the Fax-TIN program. It runs 24 hours a day, 7 days a week, and these numbers can only be used to apply for an EIN.
Step by step
- Fill in Form SS-4. Download it from irs.gov, complete it and sign it. An unsigned form gets sent back.
- Write your return fax number on it. The IRS faxes the EIN back to you, so the form needs a fax number that can receive. If you don't have one, see the section below.
- Add a cover sheet. It isn't required, but it helps the page reach the right desk. Put your name, phone number, the page count and "Form SS-4, EIN application" as the subject. You can make one here in a minute.
- Scan and send. In HonestFax, tap Scan document, photograph each page, choose United States and type the number from the table. The app shows the page count and the cost before you send.
- Keep the confirmation. When the IRS fax machine answers and takes the pages, the fax is marked Delivered. Keep that record until the EIN arrives. More on that in how to confirm a fax was received.
Getting the EIN back without a fax machine
The EIN comes back by fax, generally within 4 business days. That means you need a fax number that can receive for at least a few days after you send. Your options:
- Use a number you already have access to, such as your accountant's office or a print shop that receives faxes for customers. Write that number on the form.
- Get your own number on your phone. A HonestFax 7-Day Pass gives you a US or Canada fax number for a week, which covers the usual 4 business days, and incoming faxes arrive in the app as PDFs. HonestFax Pro keeps the number for as long as you subscribe. See how to receive a fax on iPhone.
Common mistakes
- Faxing to an old number. Third-party lists go stale. Use the IRS instructions as the source. Our IRS fax numbers by form page lists the current numbers with the date we checked them.
- Missing signature. The form must be signed and dated by the responsible party.
- No return fax number. Without it, the IRS can't fax the EIN back.
- Sending twice. Apply using one method only, so the business doesn't end up with two EINs.
Frequently asked questions
How long does it take to get an EIN by fax? The IRS says generally within 4 business days.
Does faxing Form SS-4 cost anything? The IRS doesn't charge for an EIN. You only pay for sending the fax: with HonestFax, a fax of up to 3 pages is $2.99, and your first page is on us.
Can I apply by phone instead? Only international applicants can get an EIN by telephone. Domestic applicants apply online, by fax or by mail.