020) since January 1, 1995. Hey Buddy Buck here!Washington law says that when you sell your home, you must fill out a Seller Disclosure Statement (also known as Form 17). Withing five days of accepting the buyer's offer, the seller must provide the buyer with a Seller's Disclosure Statement, also called "Form 17". By law, most sellers of real property must provide a completed Seller Disclosure Statement (aka Form 17) to any buyer. Learn more about the NWMLS Form 17 (or Seller Disclosure Statement). Almost all sellers in WA must complete and provide one to a buyer. Gov website belongs to an official government organization in the United States. Home Washington State Department of Social and Health Services. Does the owner of a manufactured home that sits on leased land have to fill out Form 17 in Washington State?