Cal. INS § 8094

Whenever an assessment is made, the secretary shall immediately notify every member by registered letter addressed to the secretary of the member at its usual post-office address, stating: (a) The amount of such loss. (b) The sum due from the member as its share. (c) To whom payment is to be made. (d) The time, not less than thirty nor more than ninety days from the date of mailing notice, when payment is to be made.