(a) An electric utility or transmission and distribution utility that owns or operates transmission facilities shall provide wholesale transmission service at rates and terms, including terms of access, that are comparable to the rates and terms of the utility’s own use of its system.
(b) The commission shall ensure that an electric utility or transmission and distribution utility provides nondiscriminatory access to wholesale transmission service for qualifying facilities, exempt wholesale generators, power marketers, power generation companies, retail electric providers, and other electric utilities or transmission and distribution utilities.

(c) When an electric utility, electric cooperative, or transmission and distribution utility provides wholesale transmission service within ERCOT at the request of a third party, the commission shall ensure that the utility recovers the utility’s reasonable costs in providing wholesale transmission services necessary for the transaction from the entity for which the transmission is provided so that the utility’s other customers do not bear the costs of the service.
(d) The commission shall price wholesale transmission services within ERCOT based on the postage stamp method of pricing under which a transmission-owning utility’s rate is based on the ERCOT utilities’ combined annual costs of transmission, other than costs described by Subsections (d-2) and (d-3), divided by the total demand placed on the combined transmission systems of all such transmission-owning utilities within a power region. An electric utility subject to the freeze period imposed by § 39.052 may treat transmission costs in excess of transmission revenues during the freeze period as an expense for purposes of determining annual costs in the annual report filed under § 39.257. Notwithstanding § 36.201, the commission may approve wholesale rates that may be periodically adjusted to ensure timely recovery of transmission investment. Notwithstanding § 36.054(a), if the commission determines that conditions warrant the action, the commission may authorize the inclusion of construction work in progress in the rate base for transmission investment required by the commission under § 39.203(e).
(d-1) The commission by rule shall establish a reasonable allowance for transmission-owning utility costs incurred to interconnect generation resources directly with the ERCOT transmission system at transmission voltage. The allowance must take into account:
(1) the potential to reduce the costs to consumers of generation interconnection;
(2) historical generation interconnection costs; and
(3) any other factor that the commission considers reasonable to accomplish the goal of this subsection.
(d-2) Costs in excess of the transmission-owning utility allowance provided by Subsection (d-1) incurred to interconnect generation resources with the ERCOT transmission system must be directly assigned to and collected from the generation resource interconnecting through the facilities.
(d-3) Not later than September 1 of every fifth year, the commission shall review and may adjust the allowance provided by Subsection (d-1) to account for inflation or supply chain issues.
(e) In this section, “ancillary services” means services necessary to facilitate the transmission of electric energy including load following, standby power, backup power, reactive power, and any other services as the commission may determine by rule.
(f) The commission shall ensure that ancillary services necessary to facilitate the transmission of electric energy are available at reasonable prices with terms and conditions that are not unreasonably preferential, prejudicial, discriminatory, predatory, or anticompetitive. On the introduction of customer choice in the ERCOT power region, acquisition of generation-related ancillary services on a nondiscriminatory basis by the independent organization in ERCOT on behalf of entities selling electricity at retail shall be deemed to meet the requirements of this subsection.
(g) The commission shall:
(1) review the type, volume, and cost of ancillary services to determine whether those services will continue to meet the needs of the electricity market in the ERCOT power region; and
(2) evaluate whether additional services are needed for reliability in the ERCOT power region while providing adequate incentives for dispatchable generation.
(h) The commission shall require the independent organization certified under § 39.151 for the ERCOT power region to modify the design, procurement, and cost allocation of ancillary services for the region in a manner consistent with cost-causation principles and on a nondiscriminatory basis.