A bill of sale benefits both the seller of a vehicle and the buyer. I Drive Safely will help you understand the importance of a Texas bill of sale.County of Harris. §. ❖ Form MV-1 must be completed and a check or money order payable to the Commonwealth of. 1. Enter the seller's name and address. Learn about bill of sale laws and requirements for the state of Texas. Get templates for buying and selling high-value items like cars, boats, and firearms.