CA Bus & Prof Code Section 2456.1

All osteopathic physician’s and surgeon’s certificates shall expire at 12 midnight on the last day of the birth month of the licensee during the second year of a two-year term if not renewed on or before that day. The board shall establish by regulation procedures for the administration of a birth date renewal program, including, but not limited to, the establishment of a system of staggered license expiration dates such that a relatively equal number of licenses expire monthly. To renew an unexpired license, the licensee shall, on or before the dates on which it would otherwise expire, apply for renewal on a form prescribed by the board and pay the prescribed renewal fee.