Though it's commonly called an employer Identification Number (EIN), there are times when you may need an EIN even though you do not have employees. An EIN can be used to identify a business entity that is legally separate from yourself, such as your corporation, partnership or retirement plan. Generally, businesses need an EIN. One exception is a sole proprietor with no employees. However, sole proprietors who must pay federal excise or payroll taxes will need an EIN, too.
Frequently asked questions about whether you need an EIN and how to apply for one can be found at the Small Business/Self Employed section of the IRS website.
If you need to apply for an EIN, complete Application for Employer Identification Number (IRS Form SS4). The instructions to Form SS-4 and Publication 1635 provide addresses and fax numbers by geographic location for submitting your application. Publications and forms are available by phone at 800-TAX-FORM (800-829-3676).