A Utah motor vehicle bill of sale, known as Form TC-843, is an official document that provides proof that a vehicle has been sold in the State of Utah. Although not legally required, the Utah DMV advises and provides private sellers with a bill of sale (form TC-843) to use when selling your car on your own.Motor Vehicle Bill of Sale (Form TC-843)– Can be used to prove the sale and purchase of either a motorcycle or automobile in the state of Utah. Create a Utah bill of sale form to document the transfer of ownership of a vehicle or another piece of personal property. Utah State Tax Commission.