Complete and sign the Title Application Form 130-U. Signed bill of sale is required for trailers and vehicles 25 years old and older.County of Harris. §. The form consists of the significant vehicle, buyer, seller, and sale data, along with affirming signatures from both parties. Forms and Downloads. The Texas bill of sale form verifies the elemental facts of the sale of personal property in exchange for a predetermined compensatory amount. For title or registration information, contact your county tax assessor-collector or the Texas Department of Motor Vehicles at. 1-888-368-4689 or 512-465-3000. Download the latest Texas Bill of Sale form for your vehicle and find details and instructions to complete this federal form with examples.