Find out what documents you will need to provide proof of sale and ownership if you are buying, selling, or gifting a vehicle. Instructions. The new owner's social security number, taxpayer identification number (TIN), or federal employer identification number (EIN) is required.How to fill out the Vehicle Bill of Sale Agreement Template? Use our fillable template to customize, deliver, and track your car sale contract in minutes. It comes with starter contractual language and eSignatures. Time Efficiency: Templates provide a pre-formatted structure, allowing you to fill in specific details quickly, saving valuable time and effort.