I'm going to show you how to send the form 17 to your sellers have them be able to fill out all of the boxes get it back and then be able to deliver it. Fill out all of this form and other papers you are attaching before you sign this form in front of a notary.Application for Extension of Time to File a Washington State Estate and Transfer Tax Return (Fill-In or Print). This is a six page document full of a bunch of questions that your customer may not recognize some of the meanings of the words. The Seller Disclosure Statement in Washington (aka Form 17) is a mandatory form all sellers must complete and give to their buyers. Withholding agents should withhold county tax based on the employee's Indiana county of residence as of Jan. Learn what residential real estate sellers must disclose to prospective home buyers when selling a house in the state of Washington. Learn more about the NWMLS Form 17 (or Seller Disclosure Statement). Almost all sellers in WA must complete and provide one to a buyer. Withholding of tax on dispositions of United States real property interests.