The proof of sale for a vehicle from a dealer is the Retail Certificate of Sale (MV-50) ("Dealer's Bill of Sale"). Instructions. The new owner's social security number, taxpayer identification number (TIN), or federal employer identification number (EIN) is required.You are free to draft your bill of sale in any language but you will need to translate it into English if you intend to use it as evidence in a legal dispute. Language and Copy Requirements. Language: You can draft your bill of sale in any language if you fill it with an accurate English translation. Translation for 'bill of sale' in the free English-Spanish dictionary and many other Spanish translations. Explore the ins and outs of Bills of Sale in our comprehensive guide, ensuring confident and secure buying and selling transactions. A Bill of Sale is also known as a sales receipt or proof of purchase. Need a Bill of Sale in Spanish? Spanish Bill of Sale forms covering transactions such as the sale of a car, electronics, jewlery and more.