Wash. Rev. Code § 28B.15.0131
For the purposes of determining resident tuition rates, resident students shall include American Indian students who meet two conditions. First, for a period of one year immediately prior to enrollment at a state institution of higher education as defined in RCW 28B.10.016, the student must have been domiciled in one or a combination of the following states: Idaho; Montana; Oregon; or Washington. Second, the students must be members of one of the federally recognized Indian tribes whose traditional and customary tribal boundaries included portions of the state of Washington, or whose tribe was granted reserved lands within the state of Washington. Federal recognition of an Indian tribe shall be as determined under 25 C.F.R. by the United States bureau of Indian affairs.
Any student enrolled at a state institution of higher education as defined in RCW 28B.10.016 who is paying resident tuition under this section, and who has not established domicile in the state of Washington at least one year before enrollment, shall not be included in any calculation of state-funded enrollment for budgeting purposes, and no state general fund moneys shall be appropriated to a state institution of higher education for the support of such student.
RCW 28B.15.0131