Cal. Ins. Code § 12110

An unearned premium reserve shall be established and maintained net of reinsurance and collateral with respect to all financial guaranty premiums. Where financial guaranty insurance premiums are paid on an installment basis, an unearned premium reserve shall be established and maintained, net of reinsurance, computed on a daily or monthly pro rata basis. All other financial guaranty insurance premiums written shall be earned in proportion with the expiration of exposure, or by such other method as may be prescribed or approved by the commissioner.