The bill of sale invoice is a document requesting payment attached to a bill of sale, which legally transfers ownership of goods from a seller to a buyer. A bill of sale is a legal form signed by the two parties to the transaction – seller and buyer – and details the type(s) of goods being sold. An invoice attached to a bill of sale will include a breakdown of the cost of all goods sold to the buyer, the total amount of money owed to the seller, and the date upon which payment must be made by the buyer. If the seller sent the items by mail, they may include shipping costs on the invoice. Once payment has been made as per the demands of the invoice, the bill of sale can be signed by both parties.