How to submit this form: Submit this form along with required documents and applicable tax to the county tag office in the county where the primary purchaser. Regardless of how you acquire a vehicle you should: check the vehicle history, transfer ownership and register your new vehicle.Write out your own full name, and that of the buyer. Bring the completed bill of sale, signed title, odometer disclosure statement, and any other required documents specific to your state. You'll need to sign the car purchase agreement (or dealer bill of sale), the title, an odometer statement, and sometimes a damage disclosure statement.