California Code, Business and Professions Code - BPC § 18822

(a) For licenses issued before January 1, 2007, a license may be renewed at any time prior to midnight on December 31 of the year in which it was issued. If not renewed, the license shall expire at that time.

(b) A license issued on or after January 1, 2007, shall expire 12 months after issuance, on the last day of the 12th month. To renew an unexpired license, the licenseholder shall, on or before midnight of the day on which the license would otherwise expire, apply for renewal on a form prescribed by the commission and pay the prescribed renewal fee. If the licenseholder is a boxer or martial arts contestant, the renewal application shall also be accompanied by the required medical examinations and test results. Renewal of an unexpired license shall continue the license in effect for one year from the expiration date of the license, when it shall again expire if it is not renewed.