A Washington residential purchase agreement is used when making an offer to purchase real estate. The agreement initiates the negotiation process.A Valid Offer And Acceptance: A real estate contract in Washington must feature specific actions that demonstrate offer and acceptance. If the Seller does not accept the Purchaser's offer, all deposits shall be returned to Purchaser. A Washington purchase agreement documents the sale of a piece of real property for a specified financial figure. Here's how it works. Send offer and acceptance form wa pdf free download via email, link, or fax.