An Employer Identification Number (EIN) is a unique nine-digit number assigned by the Internal Revenue Service (IRS) to identify a business entity. It is also known as a Federal Tax Identification Number. EINs are used to identify the tax accounts of employers and certain others. The number is formatted as XX-XXXXXXX.

Businesses in the United States are required to have an EIN if they do any of the following inside the country:

• Hire employees
• Operate as a corporation or partnership
• File tax returns for employment, excise, or alcohol, tobacco, and firearms
• Withhold taxes on income paid to a non-resident alien

EINs are issued by the IRS and include information about the state in which the corporation is registered. The agency uses EINs to identify taxpayers that are required to file various business tax returns. EINs are unique to the businesses to which they are assigned, and the same number set is never reissued to another business, even if the original employer goes out of business.

Businesses can apply for EINs directly through the IRS, which usually issues them immediately. Applying for a Federal Tax Identification number is a free service through the IRS. If a business has forgotten, lost, or misplaced their EIN number, they can call (800) 829-4933 and select EIN from the list of options to retrieve it.