Fill out and return to the Harris County Purchasing Department ONE (1) complete proposal form in an appropriately sized envelope or box. Bidding Instructions.Bid opening every Mondays at 2 PM. The bid opening has been tentatively moved online. To stream the Bid Opening Live: Click here. Vendors are required to submit written proposals that present the vendor's qualifications and understanding of the work to be performed. Form 1295 and instructions on completing and filing the form are available on the Texas Ethics Commission website.