Form SS-4 Application for Employer Identification Number is used by employers, corporations, partnerships, sole proprietors, trusts, estates, churches, government agencies, Indian tribal entities, certain individuals and others to apply for their federal EIN tax ID number. That sounds like a whole lot of employers for just one form, but Form SS-4 line 9a asks you to check one box that best describes your entity type.
Please note that the Internal Revenue Service (IRS) now has an online EIN application The online EIN application replaces the need for Form SS-4. The online EIN application asks you the questions necessary to process your form and you will get your EIN immediately upon completion. See the EIN online application link below for more information.
Form SS-4 Application for Employer Identification Number
Apply for Employer Identification Number (EIN) Online