An Employer Identification Number (EIN) is a unique nine-digit number assigned by the Internal Revenue Service (IRS) to business entities operating in the United States. EINs are used for a variety of purposes, including opening a bank account, applying for a business credit card, and filed annually with the IRS. While most businesses are required to have an EIN, there are a few exceptions. For instance, sole proprietorships with no employees and businesses with annual gross receipts of less than $5,000 are not required to obtain an EIN. In addition, certain non-profit organizations may be exempt from having an EIN if they are not engaged in fundraising activities. Given the wide range of benefits associated with having an EIN, it is generally recommended that all businesses obtain one. This number is not be be confused with a 501(c)(3) number which is a status granted by the IRS.