You will also need to submit a completed W9 form. The Local Business Tax is required of any individual or entity choosing to engage in business, profession or occupation in Hillsborough County.Visit the Bonfire EProcurement platform to register as a vendor, view bid opportunities, or login to your account to submit and track bids. Find important forms and documents for Hillsborough County vendors. Beware of unsolicited purchase orders. With this system, vendors will obtain a secure online account to create a vendor profile, update company information, and receive notification of bids. Complete editable Hillsborough County (FL) forms in minutes. Sign up Free sign up, no payment required. Free sign up, no payment required. Choose the document or form you need to continue:.