Ed. Code, § 89533

(a) Any nonacademic employee shall be required to serve only one probationary period to gain permanent status in a position or in a substantially similar position. If such an employee is promoted to a position with substantially different duties or to a position that requires additional duties and abilities, he shall serve an additional probationary period; but if he does not become permanent in the new position, he shall have the right to return to any class in which he was permanent or to the class in which he was serving before his promotion. An employee who is promoted before he completed the probationary period in the lower class and is returned to such class without having become permanent in the new position shall receive credit toward permanent status in the lower class for the period of time he had previously performed satisfactorily therein. An employee who is promoted before he completed the probationary period in the lower class shall earn permanent status in the lower class at the end of one year from the original appointment date in the lower class, provided the duties in the higher class are substantially similar to the duties in the lower class and the employee’s performance in both classes has been satisfactory.

(b) If the provisions of this section are in conflict with the provisions of a memorandum of understanding reached pursuant to Chapter 12 (commencing with Section 3560) of Division 4 of Title 1 of the Government Code, the memorandum of understanding shall be controlling without further legislative action, except that if such provisions of a memorandum of understanding require the expenditure of funds, the provisions shall not become effective unless approved by the Legislature in the annual Budget Act.