9 October 2026 • 4 minute read
Amendment to the Charge Determination Methodology: Clarifications on the Exemption Period and key considerations
On September 30, 2026, the Resolution of the National Energy Commission amending the resolution issuing the methodology for determining the charge corresponding to the electricity transmission service provided by the Supplier to Permittees with electric power generation plants, which have an interconnection contract and agreement for the electricity transmission service entered into under the Public Electricity Service Law, published on June 18, 2026, or Acuerdo de la Comisión Nacional de Energía por el que se modifica el diverso por el que se emite la metodología para la determinación del cargo correspondiente al servicio de transmisión de energía eléctrica que preste la Suministradora a las Personas Permisionarias con centrales de generación de energía eléctrica, que cuenten con contrato de interconexión y convenio para el servicio de transmisión de energía eléctrica celebrados al amparo de la Ley del Servicio Público de Energía Eléctrica, publicado el 18 de junio de 2026 (Amending Resolution to the Methodology) was published in the Federal Official Gazette (Diario Oficial de la Federación, or DOF) and entered into force on the date of its publication.
On June 18, 2026, the Resolution of the National Energy Commission issuing the methodology for determining the charge corresponding to the electricity transmission service provided by the Supplier to Permittees with electric power generation plants, which have an interconnection contract and agreement for the electricity transmission service entered into under the Public Electricity Service Law, or Acuerdo de la Comisión Nacional de Energía por el que se emite la metodología para la determinación del cargo correspondiente al servicio de transmisión de energía eléctrica que preste la Suministradora a las Personas Permisionarias con centrales de generación de energía eléctrica, que cuenten con contrato de interconexión y convenio para el servicio de transmisión de energía eléctrica celebrados al amparo de la Ley del Servicio Público de Energía Eléctrica (Methodology) was published in the DOF. As noted in our June 2026 publication, the Methodology redefines the costs applicable to the transmission service for Permittees remaining in the grandfathered regime of the Public Electricity Service Law.
According to its recitals, the Amending Resolution to the Methodology was issued as a result of the amendment to the Guidelines for the voluntary and expeditious migration of self-supply and cogeneration of electricity to the figures provided for in the Electricity Sector Law, or Lineamientos para la migración voluntaria y expedita de autoabastecimiento y cogeneración de energía eléctrica a las figuras previstas en la Ley del Sector Eléctrico (Migration Guidelines), which we also explored in our June 2026 publication. Its stated purpose is to provide legal certainty regarding the period during which the grandfathered rate will exceptionally continue to apply (Exemption Period) and to give Permittees the option to waive that exemption.
Accordingly, the Amending Resolution to the Methodology amends the Third and Fourth Transitory Articles of the Methodology. It does not replace the Methodology or modify its formula.
Key amendments
Exemption Period. The Amending Resolution to the Methodology clarifies that the Exemption Period may not begin before October 19, 2026, will have no retroactive effect, and will end on October 6, 2028.
Contractual term. The Amending Resolution to the Methodology specifies that Permittees to which the Exemption Period applies must have an interconnection contract and transmission agreement in effect. As originally published, the Methodology required those instruments to remain in effect beyond October 6, 2028.
New termination events. The Amending Resolution to the Methodology adds two events under which the Exemption Period will cease to have effect:
- Contractual termination: when the term of the interconnection contract and transmission agreement entered into under the former Public Electricity Service Law (Ley del Servicio Público de Energía Eléctrica) ends; and
- Voluntary waiver: when the Permittee voluntarily waives the Exemption Period before the National Energy Commission (Comisión Nacional de Energía), which it may do at any time.
Payment regime. If the Exemption Period ceases to have effect, transmission service charges must be paid in accordance with the Methodology or with the applicable Wholesale Electricity Market rates.
Projects with contracts expiring before October 6, 2028. Under the Amending Resolution to the Methodology, energy projects whose grandfathered contracts expire before October 6, 2028 may qualify for the Exemption Period, provided that those contracts are in effect and the projects have initiated the migration procedure.
For more information, please contact the authors.