The Employer Identification Number (EIN), also known as the Federal Employer Identification Number (FEIN) or the Federal Tax Identification Number (FTIN), is a unique nine-digit number assigned by the Internal Revenue Service (IRS) (format: XX-XXXXXXXXX) to business entities operating in the United States for the purposes of identification and employment tax reporting. Other commonly used terms for EIN are Taxpayer Id, IRS Number, Tax Id, Taxpayer Identification Number (TIN) etc.
A business needs an EIN in order to pay employees and to file business tax returns. To be considered a Partnership, LLC, Corporation, S Corporation, Non-profit, etc. a business must obtain an EIN. Also, financial institutions such as banks, credit unions, and brokerage houses will not open an account for a corporation without an EIN. Since all corporations - including ones with no income - must file at least a federal income tax return, a corporation operating or incorporated in the United States generally must obtain an EIN either before or after being issued its charter.