California Code, Business and Professions Code - BPC § 1715

Licenses issued under the provisions of this chapter, unless specifically excepted, expire at 12 midnight on the legal birth date of a licentiate of the board during the second year of a two-year term if not renewed.

The board shall establish procedures for the administration of the birth date renewal program, including, but not limited to, the establishment of a pro rata formula for the payment of fees by licentiates affected by the implementation of such program and the establishment of a system of staggered license expiration dates such that a relatively equal number of licenses expire annually.