If you are a sole proprietor or self employed, you don't need an EIN unless you pay employees and hold out taxes and give them a W2. But you can get an EIN to give out to people who pay you or to give people you pay on a 1099NEC instead of using your ssn.
EIN Employer Identification Number info
http://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Employer-ID-Numbers-EINs
