Cal. Ins. Code § 1775.3

Each surplus line broker required to make monthly installment payments shall remit them on or before the first day of the third calendar month following the end of the accounting month in which the business was done. The annual payment under Section 1775.5 shall be in lieu of an installment payment under this section for the accounting month of December. Remittances for those payments shall be made payable to the commissioner and shall be made by electronic fund transfer in accordance with Section 1775.8 or delivered to the office of the commissioner, accompanied by an installment payment form prescribed by the commissioner if remittance by electronic fund transfer is not mandatory under Section 1775.8.