A vehicle bill of sale is a document that proves the date that a sale took place and the exact monetary amount of the sale. Some states do not require a bill of sale when a vehicle is sold from one private party to another but it is still recommended that one is generated at the time of the sale.
The DMV website offers free, printable versions of state-specific bill of sale forms for the states that require them. The forms are also available at all DMV locations.
A bill of sale should always include the following: the year of the vehicle, the make and model of the vehicle, the sale price, the vehicle's identification number, both the buyer's and seller's names and the city and state the sale took place.