Definition

A TIN is a nine-digit number in the format XX-XXXXXXX, while a Social Security number has the format XXX-XX-XXXX. TINs are issued by the Internal Revenue Services (IRS) to businesses who apply online or who fill out and return form SS-4. The TIN identifies your business as a unique, taxpaying entity to the IRS. TINs are issued to all business types, including sole proprietors, churches, corporations, partnerships and government bodies.

Who Must Get an EIN

If you are in business and you have employees, you are required to get an EIN by the IRS. In addition, if you are a corporation or partnership, have a Keogh plan or file employment, excise, alcohol, tobacco and firearms taxes, you must obtain an EIN. Not all businesses are required to have an EIN: if you are a sole proprietor without employees, you can elect to use your SSN instead of your EIN for business purposes.

What to Use Your TIN For

If your business has a TIN you can use the TIN in place of the SSN for business-related purposes. For example, if you want to file a tax return for your business, you would use a TIN and not an SSN. If you want to open a checking account in your business's name, most banking institutions require that you have an TIN to identify your business before opening an account. A TIN can be used to apply for business credit.

Fraudulent Use

If you use a TIN to apply for personal credit, you could be subject to criminal charges; making false statements on a credit application is a federal crime. In addition, it's illegal to obtain an EIN under false pretenses -- unless you are applying for business purposes, you should not attempt to get an EIN. Some companies sell consumers with bad credit a new TIN with the intent to start up a separate credit file under a "file segregation" program. This program is illegal.