Name Changes are filed in District Court, in the county where you reside. Generally a Petition for Name Change and an Order for Name Change must be completed.To change the date or place of marriage or dissolution, the officiant (marriage) or clerk of court (dissolution) must complete and submit the affidavit. You can file an application to change your legal name in any district court in Washington. The person requesting a name change is called the "petitioner." Filing a Name Change Petition. A petitioner must fill out a Petition for Name Change (PDF). Bring the original Petition for Name Change, completely filled out. You may complete the name change petition online. File a Petition in the district court of the county where you live and pay the filing fee.