You can apply for a EIN or tax ID number with the IRS. This can be done online thru their site and in most cases may be free. A EIN for a business is just like a social security number for a person. Every business is assigned and must have a tax ID number (also called the EIN). The tax id number or EIN is a nine-digit number assigned by the IRS to business entities operating in the United States. The tax ID number is used to open most business bank accounts and business loans and it’s the cornerstone for building your business credit profile.