What is an EIN?
An EIN (Employer Identification Number) is a nine-digit federal taxpayer identification number issued by the IRS to U.S. businesses, trusts, estates and certain other entities. The EIN — formatted as XX-XXXXXXX — is the business equivalent of an individual SSN and is the primary identifier the IRS, banks, payroll providers and counterparties use to track an entity’s tax obligations.
Who needs an EIN?
An EIN is required for any U.S. entity with employees, partnerships, corporations, multi-member LLCs, entities that file employment, excise, or alcohol/tobacco/firearms returns, and most trusts and estates. Single-member LLCs treated as disregarded entities may also obtain an EIN for banking, payroll, and Form W-9/W-8 purposes.
How to apply
U.S. applicants apply through the IRS‘s online EIN Assistant, by fax (Form SS-4), or by mail. Non-U.S. applicants without a U.S. taxpayer identification number cannot use the online system and must submit Form SS-4 by fax or international phone to the IRS International Office, providing a Responsible Party with a valid identifier or no identifier with proper documentation.
EIN for non-U.S. businesses
Foreign entities frequently need an EIN to open a U.S. bank account, register a U.S. subsidiary, claim treaty benefits via Form W-8BEN-E, comply with FATCA, or hire a U.S. employee or contractor. Obtaining an EIN does not by itself create a U.S. tax filing obligation, but combined with U.S.-source income or a U.S. trade or business it often will.
Common pitfalls
The IRS limits responsible parties to one EIN per day per individual. EINs are tied to the legal entity at formation, not the operating business name, so post-formation conversions (LLC to corporation, foreign-to-domestic) may require a new EIN. EINs are also public-record-adjacent and may appear on filings, so confidentiality is limited.