Form SS-4 is used when applying for an Employer Identification Number (EIN). An EIN is a nine-digit number the Internal Revenue Service (IRS) assigns to employers, sole proprietors, corporations, partnerships, estates, trusts, and other entities for tax filing and reporting purposes. When starting a new U.S. business, you will generally need to apply for an EIN using Form SS-4.

Before you complete your Form SS-4, you should prepare by doing the following:

• Determine the legal name of your business.
• Determine if the business has a trade name (i.e., doing business as, or DBA) that is different from its legal name.
• Know whether the business is a corporation, partnership or LLC.
• Determine the mailing address of your business.
• Gather information about the individual responsible for the business, including their tax ID number.
• Know the business start date and closing month of the accounting year.

If you don’t know this information or your business hasn’t yet been established, you should wait until this information is known to file your Form SS-4.

You can submit your Form SS-4 on the IRS’s online application, via fax or by mail. If you use the online application, you will receive your EIN immediately. Phone applications are only available for international applicants. If you have no legal residence, principal place of business, or principal office or agency in the U.S. or U.S. territories, you can’t use the online application to obtain an EIN. In certain cases, the online application for an EIN may be rejected, in which case, you may be required to call, mail, or fax the information to the IRS instead.