A bill of sale is a legal document that records the transfer of ownership of an asset to a second party in exchange for money. A vehicle bill of sale in Illinois is used to document the purchase and sale of a car between a private seller and a buyer.Get Illinois bill of sale forms and learn how to transfer ownership of vehicles, boats, firearms, and other personal property from one party to another. A bill of sale will detail a transfer of property or sale of items between a seller and buyer. This type of document serves as legal evidence. The meaning of BILL OF SALE is a formal instrument for the conveyance or transfer of title to goods and chattels. A bill of sale is a legally binding document that shows in writing the sale or transfer of personal property from one party to another. Free Illinois Bill of Sale Forms. Legally transfer ownership of items in Illinois, whether through a sale or purchase, with a Bill of Sale (BOS). An automobile bill of sale or used vehicle bill of sale is like a receipt that proves you've transferred the car to the buyer.