● Contact the Division. An Employer Identification Number (EIN), also known as a federal tax identification number, identifies a business entity. Generally, all businesses need an EIN. An EIN is a nine-digit number that the Internal Revenue Service assigns to a business. The IRS uses the number to identify taxpayers that are required to file various business tax returns. For additional information, please contact the Internal Revenue Service at 800-829-4933 or www.irs.gov.