A hearing officer shall not:
A. engage or participate in any way in the enforcement or formulation of general tax policy other than to conduct hearings. A taxpayer or the taxation and revenue department may request that the chief hearing officer determine whether a hearing officer has engaged or participated in the enforcement or formulation of general tax policy and whether that engagement or participation affects the hearing officer's impartiality in a particular matter. To avoid actual or apparent prejudice, the chief hearing officer may designate another hearing officer for the matter; and
B. engage in ex-parte communications concerning the substantive issues of any matter that has been protested while that matter is pending. If the chief hearing officer determines that a hearing officer has engaged in prohibited ex-parte communications, the chief hearing officer shall designate another hearing officer for that matter.