Form W-9

Form W-9 (officially, the "Request for Taxpayer Identification Number and Certification")^[1] is used in the United States income tax system by a third party who must file an information return with the Internal Revenue Service (IRS).^[2] It requests the name, address, and taxpayer identification information of a taxpayer (in the form of a Social Security Number or Employer Identification Number).

The form is never actually sent to the IRS; it is maintained by the individual who files the information return for verification purposes. The information on the Form W-9 and the payment made are reported on a Form 1099.^[3]