Education Code § 1206

(a) Except as provided in subdivision (b), no person shall hereafter be elected or appointed to office as county superintendent of schools of any county who does not possess a valid credential issued by the Commission on Teacher Credentialing of the type designated in this article for each class.

(b) Where a county changes from one class to another because of an increase in the average daily attendance in the public schools of that county, the incumbent county superintendent of schools in that county shall not be prohibited from continuing in office and shall be eligible for reelection to the same office regardless of whether the incumbent county superintendent of schools possesses a valid credential otherwise required in a county of that class.