California Code, Elections Code - ELEC § 10604

(a) Notwithstanding Section 10603, if a declaration of candidacy for an incumbent member of a school district or community college district governing board or of a county board of education is not filed by 5 p.m. on the 88th day before the election, any person, other than the person who was the incumbent on the 88th day, shall have until 5 p.m. on the 83rd day before an election to file a declaration of candidacy for the elective office.

(b) This section is not applicable where there is no incumbent eligible to be elected.If this section is applicable, notwithstanding Section 10603, a candidate whose declaration of candidacy has been filed for any school district or community college district governing board election or county board of education election may withdraw as a candidate until 5 p.m. on the 83rd day before the election.