020) since January 1, 1995. Learn more about the NWMLS Form 17 (or Seller Disclosure Statement).Almost all sellers in WA must complete and provide one to a buyer. In most realestate transactions in Washington, the seller of the property must complete a "Form 17" disclosure statement and give it to the buyer. The Form 17 permits a seller to mark answers to the form questions as "Yes", "No", "I don't know", and "NA." The seller disclosure statement, also known as a seller disclosure form or Form17 is a crucial document that sellers must complete when selling their home. To be used in transfers of improved residential real property, including residential dwellings up to four units, new construction,. The current form is 6 pages long and includes most of the typical property issues requiring disclosure with a catchall question for anything left out.