138.200.  Qualifications of members — interim appointments — members to devote full time to duties — private employment prohibited. — 1.  Each commissioner shall be a qualified voter and taxpayer and resident of the state for at least five years next preceding his appointment.  At all times the state tax commission shall be so constituted that not more than two members shall be of the same political party.

  2.  In the event of a vacancy occurring while the general assembly is not in session, the governor may appoint a temporary member of the commission to serve until such time as a permanent appointment can be made with the advice and consent of the senate.

  3.  Each commissioner shall devote his full time and efforts to the discharge of his duties and shall not accept any private employment of any kind or nature while serving on the commission nor hold any other office under the laws of this state, or any city, or county, or city and county, in this state, nor any office under the government of the United States.

  4.  No commissioner or employee of the commission shall hold any position of profit, engage in any occupation or business interfering with, or inconsistent with, his duties as commissioner or employee.  No person is eligible to appointment or shall hold the office of commissioner, or be appointed by the commission, or hold any office or position under the commission, who holds any official office or position or who is a stockholder or who is in any wise pecuniarily interested in any common carrier, public utility, or any other corporation whose original assessment is made by the commission, as provided by this chapter.  The words "original assessment" as used herein shall not be held or construed to include the assessment of corporation franchise tax.