The board of equalization of each county shall consist of not less than three nor more than seven members including alternates. Such members shall be appointed by a majority of the members of the county legislative authority, and shall be selected based upon the qualifications established by rule by the department of revenue and shall not be a holder of any elective office nor be an employee of any elected official: PROVIDED, HOWEVER, The county legislative authority may itself constitute the board at its discretion. Any member who does not attend the school required by RCW
84.48.042 within one year of appointment or reappointment shall be barred from serving as a member of the board of equalization unless this requirement is waived for the member by the department for just cause.