Step 1 - Log into the vendor portal.
Step 2 - Click on the "Settings" Section
Step 3 - Click on "add attachment button" button into the W-9 Section and select the W-9 form to be uploaded.
Note: The W-9 you load will be visible to all "Customers" who have access to you as a vendor. To see which customers have access please view the related Topic "Who can see my Vendor Data?".