Learn how to fill out the Washington state vacant land purchase and sale agreement in our step-by-step guide! A Washington residential purchase agreement is used when making an offer to purchase real estate.The agreement initiates the negotiation process. Any personal property included in the sale shall be included in the fulfillment deed. 9. Washington Land Contract Template. A Washington land contract is a formal sale agreement between two parties transferring ownership of vacant real estate. The completed document will describe the property being sold, purchase price, closing date, and closing costs. A Washington purchase agreement documents the sale of a piece of real property for a specified financial figure.