California Code, Insurance Code - INS § 11624.2

(a) An insurer shall acknowledge in writing within 15 days the receipt of a request for the endorsement of an assigned risk policy.  The mailing of the endorsement within 15 days of receipt shall constitute acknowledgement of receipt.

(b) Upon receipt of a completed request for an endorsement that contains all information necessary for the issuance of an endorsement, the insurer shall issue and mail the endorsement to the insured within 30 days of the request for the endorsement.

(c) As used in this section, “endorsement” means an amendment of a policy, such as a loss payee endorsement, the addition or deletion of insureds, or the addition or deletion of coverage.