Cal. Fin. Code § 408

The commissioner, in addition to the annual assessment, shall collect from each bank authorized to engage in the trust business, to defray the cost of examination, a fee for the examination, as determined by the commissioner. In determining the fee, the commissioner may use the estimated average hourly cost, including, but not limited to, overhead, for all persons performing the examination, plus, if in the opinion of the commissioner it is necessary for any examiner engaged in the examination to travel outside this state, the travel expenses of the examiner. The commissioner shall assess the fee upon completion of the examination of the trust company or trust business and shall mail or otherwise deliver an invoice for the fee to the institution. The institution shall pay the fee within 30 days after the invoice is mailed or otherwise delivered to it.