Employer Identification Number is a nine-digit federal tax identification number issued by the US Internal Revenue Service to identify a business entity for tax, payroll, and banking purposes.
The Employer Identification Number (EIN), sometimes called a Federal Employer Identification Number (FEIN) or Federal Tax Identification Number, is a nine-digit number formatted as XX-XXXXXXX that the IRS assigns to businesses operating in the United States.
Every US corporation, LLC with employees, partnership, non-profit, trust, and estate needs one to file federal tax returns, open a US business bank account, run payroll, hire employees, or apply for most US business licenses. Sole proprietors without employees may use their Social Security Number instead, but most still obtain an EIN to keep personal and business finances separate.
Foreign founders forming a US LLC or C-Corp can apply by filing IRS Form SS-4 by fax or mail; phone applications are reserved for entities with a US-based responsible party who has an SSN or ITIN. Processing typically takes four to six weeks for non-US applicants, though same-day issuance is available online for entities whose responsible party has an SSN/ITIN.
The EIN never expires, is not transferable between entities, and once issued cannot be cancelled - only the IRS account associated with it can be closed.
You will need an EIN before opening a US business bank account, registering with state tax authorities, hiring W-2 employees or paying 1099 contractors, filing Form 1120 (C-Corp) or Form 1065 (partnership/multi-member LLC), or signing up for Stripe Atlas, Mercury, Brex, or any US payroll provider.
Foreign founders typically apply for an EIN within the first two weeks after the state filing is approved, since most banking and payment-processor onboarding requires the EIN letter (CP 575) as proof of entity formation.
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