Tex. Utilities Code § 53.004: EQUALITY OF RATES AND SERVICES.

(a) A public utility may not directly or indirectly charge, demand, or receive from a person a greater or lesser compensation for a service provided or to be provided by the utility than the compensation prescribed by the applicable tariff filed under Section 52.251.

(b) A person may not knowingly receive or accept a service from a public utility for a compensation greater or less than the compensation prescribed by the tariff.

(c) This title does not prevent a cooperative corporation from returning to its members net earnings resulting from its operations in proportion to the members' purchases from or through the corporation.

Acts 1997, 75th Leg., ch. 166, Sec. 1, eff. Sept. 1, 1997.