Notwithstanding Section 20037, “final compensation” for the purposes of determining any pension or benefit with respect to a school member who retires or dies on or after January 1, 2000, and with respect to benefits based on service with a school employer, means the highest annual compensation that was earnable by the school member during any consecutive 12-month period of employment preceding the effective date of his or her retirement or the date of his or her last separation from service if earlier.