Typically, this involves two documents: a financing agreement (basically a loan document outlining the details and terms of the loan) and a promissory note. The key documents in a seller financing transaction include: (1) Purchase Agreement; (2) Promissory Note; and (3) Deed of Trust.Owner financing is an alternative to mortgages, where property owners finance purchases on the buyer's behalf. Seller financing can help a buyer pay more for the business than if the deal were financed only through traditional financing sources.