Form SS-4 Instructions & Fax Guide 2026

What Is Form SS-4?

Form SS-4, Application for Employer Identification Number (EIN), is used by businesses and other entities to apply for an Employer Identification Number from the IRS. An EIN is a nine-digit number assigned by the IRS for tax filing and reporting purposes — essentially a Social Security number for your business.

Why You Might Need Form SS-4

You need an EIN when starting a business, hiring employees, or opening a business bank account. Common scenarios include:

• •Starting a new business (LLC, corporation, partnership, or sole proprietorship with employees)
• •Hiring your first employee — an EIN is required before issuing W-2s
• •Opening a business bank account — most banks require an EIN
• •Filing business tax returns or applying for business licenses
• •Purchasing or inheriting an existing business

Where to Fax Form SS-4 in 2026

Step-by-Step: How to Fill Out & Fax Form SS-4

Using FaxFlow to Send Form SS-4 Easily

FaxFlow eliminates the hassle of traditional faxing. No driving to a fax machine, no busy signals, and no wondering if your form was received.

Common Mistakes to Avoid

• •Applying for multiple EINs when only one is needed
• •Using your SSN instead of applying for an EIN when required
• •Incomplete responsible party information (name and SSN/ITIN required)
• •Applying by fax when online application would give immediate results
• •Not signing the form before faxing

FAQ Section

• How long does it take to get an EIN by fax?

  

  Under the IRS Fax-TIN program, you can receive your EIN by fax within 4 business days. If you provide a fax number on your application, the IRS will fax a confirmation with your new EIN.

• Can I apply for an EIN online instead of faxing?

  

  Yes, the IRS offers an online EIN application at IRS.gov/EIN that provides your number immediately. However, faxing is useful if you need to include supporting documents or if the online system is unavailable.

• Do I need an EIN if I'm a sole proprietor?

  

  You only need an EIN as a sole proprietor if you have employees, file certain tax returns (excise, alcohol, tobacco, firearms), or have a Keogh plan. Otherwise, you can use your SSN.

• Is there a fee for getting an EIN?

  

  No. The IRS does not charge a fee for issuing an EIN. Be cautious of third-party websites that charge for this free service.

• Can I fax Form SS-4 from my phone?

  

  Yes. Use FaxFlow to fax your completed Form SS-4 directly from your iPhone or Android phone. Simply scan or upload the form and send to 855-641-6935.