Cal. PROB § 403

(a) The term of office of a probate referee is four years, expiring June 30. A person may be appointed to complete the unexpired term of office of a probate referee whose appointment is revoked or is otherwise terminated. For a period of five years from the date of expiration of the term of office, a person who had been appointed to act as a probate referee is eligible for reappointment. (b) If the Controller increases the number of probate referees in a county, the Controller shall stagger the terms of the new appointees so that one-quarter, or as close to one-quarter as possible, of the terms of the probate referees in that county expire on June 30 of each succeeding year.