Cal. Bus. & Prof. Code § 4545
Except as provided in Section 4545.2, a license that has expired may be renewed at any time within four years after its expiration on filing an application for renewal on a form prescribed by the board, payment of all accrued and unpaid renewal fees, and payment of all fees required by this chapter. If the license is renewed more than 30 days after its expiration, the holder, as a condition precedent to renewal, shall also pay the delinquency fee prescribed by this chapter. Renewal under this section shall be effective on the date on which the application is filed, on the date on which the renewal fee is paid, or on the date on which the delinquency fee, if any, is paid, whichever last occurs. If so renewed, the license shall continue in effect through the date provided in Section 4544 which next occurs after the effective date of the renewal, when it shall expire if it is not again renewed.
A certificate which was forfeited for failure to renew under the law in effect before October 1, 1961, shall, for the purposes of this article, be considered to have expired on the date that it became forfeited.
Ca. Bus. and Prof'l. Code § 4545