Washington State does not publish any official state-wide forms for name change. The Name Change brochure written by the Northwest Justice Project does have sample forms. Some district courts (including King County and Thurston County) have their own forms and instructions. Contact your local district court to see if they have forms available for you to use.
King County District Court — If you live in King County, the King County District Court has published forms and instructions for you to follow. If you live in another county, contact your local district court to see if they have their own forms for you to use.