Whenever the county legislative body shall combine the duties of any county officers the salary of the person discharging the duties of such offices shall be fixed at a sum not exceeding the highest salary paid to either of the officers whose offices are so combined, in addition to an amount not exceeding one-half of the salary fixed for the other officer, when only two offices are combined, or when more than two offices are combined, in addition to such highest salary, one-third of the combined salaries of such other officers.
Utah Code § 17-16-20