California Code, Revenue and Taxation Code - RTC § 6480.3

The supplier or wholesaler shall file his or her prepayment form together with a remittance of the prepayment amounts, if any, required to be collected pursuant to Section 6480.1 payable to the State Board of Equalization, on or before the last day of the month following the monthly period to which the prepayment form or each prepayment relates.