Cal. Veh. Code § 23301.8
Where an issuing agency permits pay-by-plate toll payment as described in subdivision (e) of Section 23302, it shall communicate, as practicable, the pay-by-plate toll amount in the same manner as it communicates other toll payment methods. The issuing agency shall provide publicly available information on how pay-by-plate toll payment works, including the toll amount, process for payment, and period of time a vehicle has to resolve the payment before an issuing agency may process the trip as a violation under Section 40255. Communication of this information may include the Department of Transportation's approved signage, posting of information on the issuing agency's Internet Web site, media advertising, public meeting or disclosure as required by the issuing agency's policies, or other methods of communication. Except where the issuing agency has an agreement with a vehicle owner that specifies in advance any administrative fees that will be imposed on the owner for pay-by-plate toll payment, administrative costs shall be incorporated into the pay-by-plate toll amount, and no additional administrative costs shall be added above the posted pay-by-plate toll amount.
Ca. Veh. Code § 23301.8