CA Educ Code Section 45201

(a)

The governing boards of any school district may accept the resignation of any employee and may fix the time when the resignation shall take effect, which, except as noted in subdivision (b), shall not be later than the close of the school year during which the resignation is received by the board.

(b)

Notwithstanding any other provision of law, an employee and the governing board of a school district may agree that a resignation will be accepted at a mutually agreed upon date not later than two years beyond the close of the school year during which the resignation is received by the board.