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Publication 80

1. Employer Identification Number (EIN)(p5)

An employer identification number (EIN) is a nine-digit number that the IRS issues. Its format is 00-0000000. It is used to identify the tax accounts of employers and certain other organizations and entities that have no employees. Use your EIN on all of the items that you send to the IRS and SSA for your business.
If you do not have an EIN, you may apply for one online. Go to and enter "EIN" in the search box. You may also apply for an EIN by calling 267-941-1099, or you can fax or mail Form SS-4, Application for Employer Identification Number, to the IRS. Do not use a social security number (SSN) in place of an EIN.
If you do not have an EIN by the time a return is due, file a paper return and enter "Applied For" and the date that you applied for it in the space shown for the number. If you took over another employer's business, do not use that employer's EIN.
You should have only one EIN. If you have more than one, write to the IRS office where you file your returns using the "without a payment" address in the Instructions for Form 941-SS, Instructions for Form 944, or Instructions for Form 943. Or call the IRS Business & Specialty Tax Line at 1-800-829-4933. Persons who are deaf, hard of hearing, or have a speech disability (TDD/TTY users) may call 1-800-829-4059. The IRS will tell you which EIN to use.
For more information, see Publication 1635, Employer Identification Number: Understanding Your EIN, or Publication 583, Starting a Business and Keeping Records.