Use a Promissory Note and Mortgage or Deed of Trust If you're familiar with traditional mortgages, this model will sound familiar. Talk to a real estate attorney for help in crafting an agreement.With seller financing, you are essentially acting like a bank. Seller financing is an agreement in real estate where the seller handles the mortgage process rather than a financial institution. Seller financing, also known as owner finance, is a real estate transaction where the seller acts as the lender and finances the buyer's purchase. To avoid a worstcase scenario, follow these pointers on drafting a contract that guards your interests as the seller and financier. What loan documentation should you use in a seller-financed real estate deal? Land Contract, Deed of Trust, Mortgage, or something else entirely?