Cal. Health & Safety Code § 18109

Except as otherwise provided in this part, every registration card for a manufactured home, mobilehome, or commercial coach subject to annual registration shall expire at midnight on the expiration date indicated on the registration card and shall be renewed prior to that expiration. The department, upon presentation by the registered owner of the registration card or potential registration card last issued and receipt of the proper renewal fees, shall renew the registration of a manufactured home, mobilehome, or commercial coach.