Sole proprietors need to have an EIN only if they have one or more employees, if they have a Keogh plan, or if they are required to file excise tax forms such as those for sales tax, alcohol or tobacco.
If you purchase a business for which an EIN is needed, use your own EIN or get a new one--don't use the EIN of the previous owner. If you operate more than one business as a sole proprietor, you should use the same EIN for each one; if you operate businesses in forms other than sole proprietorship, you'll need a separate EIN for each business entity.
To apply for an EIN, you can file a paper Form SS-4, Application for Employer Identification Number, with the appropriate IRS Service Center for your state. If you apply by mail, it generally takes about four weeks to receive the number. If you need to file your tax return before you receive the EIN, write "applied for" in the space where the EIN should go.
You can also get an EIN immediately over the phone by calling the number of the Tele-TIN in the chart on the next page; however, you'll still need to fill out a paper SS-4 form and mail or fax it to the Service Center within 24 hours. The IRS representative will give you the correct fax number. The advantage of using this system is that you will receive the EIN immediately and you can use it on your tax forms right away.
Form SS-4, Application for Employer Identification Number
The file is in Adobe portable document format (PDF), which requires the use of Adobe Acrobat Reader.
For background information as well as information on related topics, see our discussion of Federal Employer Identification Numbers