Employer Identification Number (EIN) is a unique nine-digit tax identification number issued by the Internal Revenue Service (IRS) in the U.S. to businesses for tax and compliance purposes. It is required for organizations to hire employees, manage payroll, file taxes, and open business bank accounts.

While EIN is primarily used in the U.S., businesses managing an external workforce across multiple regions may need to comply with local tax and labor regulations. In India, similar employer registrations include EPFO (Employees’ Provident Fund Organization) and ESIC (Employees' State Insurance Corporation) for managing workforce benefits and compliance.