(a) The rates that a gas utility or municipally owned utility charges a state agency may not include an amount representing a gross receipts assessment, regulatory assessment, or similar expense of the utility.
(b) An expense under Subsection (a) that is reasonable and is not recovered from a state agency under this section may be recovered from other customers of the gas utility or municipally owned utility.
(c) A gross receipts assessment, regulatory assessment, or similar expense of the utility does not include a payment to a municipality under a contract, franchise, or other agreement.