Transfer, Replace, or Change Title To prove vehicle ownership, it's important to have a valid, up-to-date, and accurate Certificate of Title. Complete the new owner information on the back of the certificate and sign it.Bill(s) of sale, if needed to establish a complete chain of ownership. Visit the California DMV's website and download a bill of sale. A bill of sale is a legal document that serves as proof of purchase and, in some cases, records a transfer of ownership — in this case, for a vehicle. This is the motor number or serial number required for identification purposes. Identification of the Parties: Clearly state the buyer and seller's full names and addresses. 2. The bill of sale is not a form of title, but you could use it to obtain the vehicle's title from the DMV.