How to Fax Form SS-4 to IRS: A 2026 Guide for EIN Application Submission

By Michael Chen · Published September 17, 2025 · Updated January 17, 2026 · 4 min read

Applying for an Employer Identification Number (EIN) is a critical first step for any new business. While the online application is fastest, it's not always available—especially if you have a foreign address, are applying for a specific entity type, or simply prefer a paper trail.

Faxing Form SS-4 is the best alternative to mail. It cuts the processing time from 4–6 weeks down to just 4 business days.

In this guide, we'll cover the exact fax numbers to use in 2026, how to prepare your form to avoid rejection, and the fastest way to send it without hunting for a fax machine.

Where to Fax Form SS-4 (2026 IRS Fax Numbers)

The IRS routes your application based on where your business is legally located. Sending your form to the wrong number will delay your EIN significantly. For more details, see our guide on IRS Fax Numbers.

Which Number Should You Use?

• US Residents: If your principal place of business, office, or agency, or legal residence (in the case of an individual) is located in one of the 50 states or the District of Columbia, use 855-641-6935.
• No US Residence: If you have no legal residence, principal place of business, or principal office or agency in any state, use 855-215-1627.
• International: If you are applying from outside the U.S., use 304-707-9471. Note that long-distance charges may apply if you use a traditional phone line.

Step-by-Step: How to Fax Form SS-4

Faxing is simple, but the IRS is strict about legibility and completeness. Follow these steps to ensure your application is processed on the first try.

1. Download and Complete Form SS-4

Download the latest version of Form SS-4 (PDF) directly from the IRS website.

• Type or Print Clearly: If possible, fill out the PDF on your computer before printing. If handwriting, use black ink and block letters.
• Sign and Date: The IRS will reject unsigned forms. Ensure the "Responsible Party" signs the form.
• Include Your Fax Number: This is crucial. On Line 18c, write your own fax number. The IRS will use this to fax your EIN confirmation letter (Notice CP 575) back to you.

2. Prepare a Fax Cover Sheet

Never send a loose form. A cover sheet protects your information and ensures the document gets routed correctly. Use our free fax cover sheet generator to create one in seconds.

• To: Internal Revenue Service (EIN Operation)
• From: [Your Name / Business Name]
• Subject: Form SS-4 Application
• Pages: [Total number of pages, usually 2 including cover]
• Contact Info: Your phone number and email in case of issues.

3. Send the Fax (No Machine Needed)

You don't need a physical fax machine to send documents to the IRS. Online fax services are secure, faster, and provide a digital audit trail.

Using mFax.to:

1. Scan or Upload: Take a clear photo of your signed Form SS-4 or upload the PDF.
2. Enter Recipient: Type in the correct IRS fax number (e.g., 855-641-6935).
3. Send: Click send. The service handles the transmission securely over the phone network.

4. Wait for Your EIN

The IRS typically processes faxed SS-4 applications within 4 business days.

• If you provided a fax number: You will receive your EIN confirmation letter by fax.
• If you did not: The confirmation will be mailed to the address on the form, which can take 4–6 weeks.

Common Mistakes to Avoid

Submitting Form SS-4 can be tricky. Avoid these common errors to prevent rejection:

1. Illegible Handwriting

The IRS uses optical character recognition (OCR) and manual data entry. If they can't read your name or address, they can't assign an EIN. Always type the form if possible.

2. Missing Responsible Party SSN/ITIN

The "Responsible Party" (Line 7a) must be an individual with a valid Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN). You generally cannot use another entity's EIN here unless strictly allowed under specific exceptions.

3. Duplicate Applications

Do not fax the form multiple times. This confuses the system and creates duplicate assignments. If you haven't heard back after 4 business days, verify your fax transmission receipt before resending.

4. Not Providing a Return Fax Number

If you want your EIN quickly, you must fill in Line 18c with a fax number where you can receive the confirmation. Without it, you're stuck waiting for snail mail.

Ready to Get Your EIN?

Don't let paperwork slow down your business launch.

1. Download Form SS-4.
2. Fill and Sign it carefully.
3. Fax it to the correct number using mFax.to for a secure, instant transmission.

Get your business official today!

For related IRS faxing guides, see our complete IRS fax numbers directory and our guide on faxing Form 2553 for S-Corp election.