Instructions. The new owner's social security number, taxpayer identification number (TIN), or federal employer identification number (EIN) is required. Yes, you need a bill of sale.State the terms and odometer reading on the BOS. Carefully examine all documents before you pay for the vehicle. What should you include in your vehicle bill of sale? Payment details: Write down the sale price and how you agreed to be paid. In most cases, the buyer will pay a lump sum. My buyer is getting a loan - I think it's a personal loan - and his credit union wants to see a bill of sale. Make sure you get the buyer's correct and complete name and physical address.