Cal. Bus. & Prof. Code § 7880
A certificate of registration as a geologist or as a specialty geologist or as a geophysicist or as a specialty geophysicist shall expire at 12 a.m. of the last day of the birth month of the certificate holder during the second year of a two-year term if not renewed. To renew an unexpired certificate, the certificate holder shall, on or before the date of expiration of the certificate, apply for renewal on a form prescribed by the board, and pay the renewal fee prescribed by this chapter.
For purposes of implementing the distribution of the renewal of registrations throughout the year, the board may establish a system of staggered certificate expiration dates and a pro rata formula for the payment of renewal fees by certificate holders affected by the implementation of the program.
Ca. Bus. and Prof'l. Code § 7880