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).

The form is never actually sent to the IRS; it is maintained by the individual who files the information return for verification purposes.

However, if the payee certifies on the W-9 they are not subject to backup withholding they generally receive the full payment due them from the payer.

Financial institutions sometimes send Form W-9 to a customer to request information.

[6]: 12 Some certified public accountants consider it best practice to ensure the completion of Form W-9 by payees before issuing any payments.