PSC Procedural Statement: W-9/W-8 & Vendor (Supplier) Authorization

Effective Date: March 22, 2021


This PSC Procedural Statement sets forth university requirements for supplier (vendor) registration prior to the issuance of a purchase order or payment.

Procedural Statement

The Procurement Service Center (PSC) requires that external suppliers (vendors) register through the CU Supplier Portal in order for the University to purchase goods or services from the supplier, pay for goods or services from the supplier, or refund the supplier in full or in part for a payment the supplier previously made to the University. Note that in the case of refunds, only non-individuals -- e.g., companies, associations, etc. -- need to register, and then only if they are not Sponsors. For Sponsors and individuals who are recipients of refunds, see Exceptions, below.

Periodically, the PSC may require an updated registration, for example, to ensure correct reporting of Tax Identification Number (TIN)/name combinations and to provide evidence that a payee is a valid individual or business (thus minimizing the risk of making inappropriate payments to fraudulent entities); and/or to ensure accurate reporting of business classifications.

The Supplier Portal registration process replaces the submission of paper W-9 and W-8 forms to the PSC.


  • Study subject payments. Study subjects submit the paper W-9 (IRS form) instead of registering through the Supplier Portal. The study subject's W-9 form must accompany the Study Subject Payment (SSP) form to ensure that the individual is correctly set up under the Clinical Trial supplier record.
  • Refunds to Sponsors. Tax documents are not needed in order to return unused funds to Sponsors on the Payment Authorization (PA) form. 
  • Reimbursements/refunds to individuals. Tax documents are not needed in order to issue reimbursements or refunds on the Non-Employee Reimbursement-International (NRI) form. Therefore, non-employees who are recipients of reimbursements or refunds do not need to register through the Supplier Portal or submit W-9 forms.
  • Cash awards and stipends on the Payment Authorization (PA) form. The payee's paper W-9 (IRS form) must accompany the PA form to ensure that the individual is correctly set up.
  • CU employees/students. CU employees and CU students are not considered to be external suppliers. (Furthermore, employee/student TIN information is already on file.)

Related Information

Related Administrative Policy Statements (APS), Other Policies and Procedures