Form W-9 is the IRS form used by a company to request your taxpayer identification number. You may get a blank Form W-9 to fill out if you or your business are hired to provide services to another company. Most often, Form W-9 is sent to independent contractors, consultants, and other self-employed workers.

It requests the name, address, and taxpayer identification information of a taxpayer (in the form of a Social Security Number or Employer Identification Number)