Cal. Pub. Util. Code § 755
(a) It is the intent of the Legislature that:
(c) The commission shall determine through existing regulatory mechanisms the reasonableness of transaction costs charged to customers that choose to pay an electrical, gas, or water corporation by a credit card or debit card bill payment option pursuant to this section. The commission shall determine how any associated costs or potential savings as a result of those customers paying by the credit card or debit card payment option shall be passed on to electrical, gas, or water corporation customers. In determining how these savings or costs are passed on to customers, the commission shall do the following: