Cal. Ins. Code § 11064

A society shall provide specifically in its certificates that if its reserves become impaired, its board of directors or corresponding body may require that the owner pay to the society the amount of the owner’s equitable proportion of the deficiency as ascertained by its board, and that if the payment be not made it shall stand as an indebtedness against the certificate and draw interest not to exceed the rate specified for certificate loans under the certificate, or if none is specified, 6 percent per annum compounded annually.