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IRS.gov Website

Frequently Asked Tax Questions

Small Business/Self-Employed/Other Business - Form SS-4 & Employer Identification Number (EIN)

  1. Is an employer ID number the same as a tax ID number?
  2. Does a small company need a tax ID number?
  3. Under what circumstances am I required to change my employer identification number (EIN)?
  4. Do businesses have to obtain the taxpayer identification number (TIN) from vendors and keep it somewhere on file?

Rev. date: 1/1/2011

Is an employer ID number the same as a tax ID number?


Rev. date: 1/1/2011

Does a small company need a tax ID number?


Rev. date: 3/16/2011

Under what circumstances am I required to change my employer identification number (EIN)?

If you already have an EIN, and the organization or ownership of your business changes, you may need to apply for a new number.
Some of the circumstances under which a new number is required are as follows:
This list is not all inclusive. Please refer to the website under Business, then Employer ID Numbers.

Rev. date: 1/1/2011

Do businesses have to obtain the taxpayer identification number (TIN) from vendors and keep it somewhere on file?

In general, businesses are required to obtain the TIN from vendors if they are required to file any information return, document or other statement that calls for the taxpayer identification numbers (TINs) of other taxpayers. Form W-9 (PDF), Request for Taxpayer Identification Number and Certification, can be used to make the request. The business should also maintain the verification of these numbers in their records.