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Form SS-4: Application for Employer Identification Number (EIN)
Form SS-4 is the IRS application for an Employer Identification Number, the 9-digit number businesses, trusts, estates and other entities use for tax filing and reporting.
Internal Revenue Service · Edition shown: Rev. December 2025 · 2 pages
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IRS also has an online route: Apply for an EIN online.
This page is general information, not legal, tax or immigration advice, and not a substitute for advice from a qualified professional.
Who uses Form SS-4
Employers, sole proprietors, corporations, partnerships, estates, trusts, churches, government agencies and certain individuals file Form SS-4 to get an EIN. The EIN is for your business activities only: don't use it in place of your Social Security number or ITIN.
A sole proprietor needs only one EIN, however many businesses or trade names they run. You also don't need a new one just because you add another place of business. A sole proprietorship that incorporates or enters a partnership does need a new EIN.
If your entity has a legal residence, principal place of business or principal office in the United States or a U.S. territory, the IRS recommends its online EIN application instead of this form. You can use the number as soon as you receive it.
How and where to send it
Online: the IRS's online EIN application is open to entities formed in the U.S. or its territories with a principal place of business there, where the responsible party has an SSN or ITIN. You must finish in one session, and it times out after 15 minutes of inactivity. Check the IRS EIN page for its hours.
By fax or mail: send the completed Form SS-4 to the fax number or address listed under How To Apply for an EIN in the instructions. Numbers differ for U.S. states, U.S. territories and applicants outside the U.S. If you have no U.S. or territory presence, you can also apply by phone using the number in the instructions; the IRS no longer issues EINs by phone to domestic applicants.
Use only one method per entity, so you don't end up with more than one EIN for it.
Fees
The IRS doesn't charge for an EIN. It says you never have to pay a fee for one, and warns about websites that charge for this service.
Deadlines
The form itself has no filing deadline, but allow time. The IRS says to complete Form SS-4 at least 4 to 5 weeks before you need an EIN if you're applying by mail. Mailed applications take about 4 weeks, faxed ones generally 4 business days, and online applicants get the EIN right away.
The IRS issues only one EIN per responsible party per day, whichever method you use. If the responsible party changes later, report it within 60 days on Form 8822-B.
Common mistakes
- Entering a legal name on line 1 that doesn't exactly match the entity's legal documents, such as its charter or trust agreement.
- Naming a company as the responsible party on line 7a. Unless the applicant is a government entity, the responsible party must be an individual.
- Checking more than one box on line 10. Pick the single reason that applies.
- Applying online and again by fax or mail for the same entity, which can produce duplicate EINs.
- Leaving the form unsigned. A signature is required, and a third-party designee's authorization isn't valid without it.
- Paying a third-party website for an EIN the IRS issues at no cost.
IRS's own instructions
About this copy
- Form
- Form SS-4: Application for Employer Identification Number
- Issuer
- Internal Revenue Service
- Edition shown
- Rev. December 2025
- Source
- The blank PDF on www.irs.gov
- Last checked
- Against the issuer's site on
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