A Deadline You Cannot Meet Yourself Closes September 18. Your Power Supplier Has to Meet It.

Two Acuerdos published in the Diario Oficial de la Federación on June 18, 2026 changed how the transmission charge is calculated for electricity generation permits granted under the Ley del Servicio Público de Energía Eléctrica — the pre-2014 legacy regime under which a large share of foreign-owned plants in Mexico still buys its power.

One, issued by the Comisión Nacional de Energía, replaces the methodology. Its Transitorio PRIMERO reads: "El presente Acuerdo entra en vigor a partir del 19 de octubre de 2026."

The other, issued by the Ministry of Energy, opens a voluntary and expedited route out of the legacy figures into the structures of the Ley del Sector Eléctrico.

They are joined by one condition, and it has two dates on it.

The two dates, and why they will not move

The methodology does not apply between October 19, 2026 and October 6, 2028 to permit holders that meet both conditions of Transitorio TERCERO: their interconnection contract and Transmission Agreement remain in effect beyond October 6, 2028, and they have started the voluntary migration procedure.

Read the second condition carefully. It requires starting the procedure "mediante el registro de la manifestación de interés para participar en dicho procedimiento y la presentación de la solicitud de migración correspondiente" — registration of the expression of interest and submission of the migration application. Two filings, not one.

Article 17, section II of the Guidelines sets the windows:

These are fixed calendar windows, not periods running from a triggering event. And Article 5, section V removes any argument about whether they can be moved: "Los plazos establecidos en los calendarios previstos en los artículos 17 y 18 de los Lineamientos, los cuales son improrrogables."

The enforcement is equally plain. Article 24, section VIII treats inactivity as withdrawal from the procedure. Article 32 provides that if the applicant fails to take the next step by the business day following a deadline, the procedure is closed and the authority issues a record of the omission.

We read all sixty-one articles and thirteen transitional provisions looking for a discretion to extend. There is none.

Start with the name, because the name is misleading

So much for the calendar. Now the substance — because what the deadline protects you from is not what its name suggests.

The instrument is called a methodology for the transmission service charge. Numeral 3.2 sets out what it actually computes:

CST = ISPTEE + ISPDEE + ISOCENACE + ISCnMEM

Four components: public transmission service, public distribution service, CENACE operating service, and non-market ancillary services. Numeral 2.1 defines the Cargo the same way — the sum of amounts determined by CENACE across all four, drawn from the Market Settlement.

So a charge labelled "transmission" carries distribution, system operation and ancillary services inside it.

And for renewable and cogeneration plants there is a fifth component: the energy bank

Transitorio QUINTO requires the charges under numeral 3.2 to include the amounts resulting from compensated energy, in accordance with "la cláusula décima quinta, fracción XV.3, inciso ii) del contrato de interconexión correspondiente."

That clause of the Contrato Legado — a contract executed under the now-repealed LSPEE and still in force — is headed Energía de Ajuste and covers energy delivered or received within the Banda de Compensación. In commercial terms it is what the industry calls the energy bank: the mechanism that lets surplus generation in some hours offset shortfalls in others. It is the economic engine of a self-supply scheme, and the reason the arrangement was worth joining.

Subsection ii) is the shortfall side — where the balance favours the Suministrador, meaning the permit holder pays. It computes:

MEA2ₘ = Σ (Aₜ × PEA2ₜ)

where Aₜ is adjustment energy in kilowatt-hours and PEA2ₜ is its price in pesos per kilowatt-hour, calculated under Annex F of the contract.

Quantity of energy multiplied by a price of energy is a commodity settlement. It is not consideration for the use of a network. So the instrument folds the cost side of the energy bank into a charge named for a service — and it does so by pointing at a numbered clause of a contract signed under a repealed statute.

That relocation is the point. What used to be an energy line in a long-term contract now sits inside a regulated charge that, under numeral 3.5, the CNE may revise and adjust at any time, on its own initiative or at the Suministradora's proposal. The hourly-shortfall economics of the scheme move from the contract to an administrative instrument that can change without anyone renegotiating anything.

The clause has two legs. Only one was moved.

Subsection XV.3 settles the bank in both directions, and the two are symmetrical in form:

Same energy quantity, Aₜ. Two different prices — PEA1ₜ when the balance runs in the permit holder's favour, PEA2ₜ when it runs against — both calculated under Annex F.

Transitorio QUINTO incorporates subsection ii) into the regulated charge. It says nothing about subsection i).

Nothing was taken away. The credit leg still operates; it simply was not moved. But the consequence is that the two legs of a single settlement mechanism now sit under different instruments. What the permit holder pays is inside a charge the CNE may revise and adjust at any time under numeral 3.5, on its own initiative or at the Suministradora's proposal. What the permit holder receives stays exactly where it was — in a contract that can only be changed by agreement.

The spread between PEA2ₜ and PEA1ₜ is the real cost of running the bank. After October 19, 2026, one side of that spread can be widened by administrative act while the other side stands still.

The provision is also provisional: Transitorio QUINTO applies "en tanto se actualicen las Reglas del Mercado."

I. If you hold the permit

You owe the charge to the Suministradora — which the methodology defines as the Federal Electricity Commission itself.

The prior framework is not amended. It is voided. The first sentence of Transitorio SEGUNDO leaves without effect all administrative provisions, acuerdos, resolutions and administrative acts applicable to the determination of these charges for LSPEE permit holders. The "postage stamp" treatment traces to Ministry of Energy communication SPEDT/200-523-09 of December 16, 2009, implemented by the extinct CRE in RES/066/2010 and RES/194/2010 — all cited in the recitals, all now displaced.

Your agreements were amended without a signature. The second sentence of the same transitorio: "Todas las referencias a la metodología de transmisión previstas en dichos contratos y convenios se entienden hechas a la metodología emitida a través del presente Acuerdo."

There is no rate stability. Numeral 3.5 permits the CNE to revise and adjust the methodology at any time, on its own initiative or at the Suministradora's proposal. Whatever the first invoice under the new methodology shows is not a fixed baseline.

Open Annex F. Both prices — PEA1ₜ and PEA2ₜ — are set under Annex F of the interconnection contract, not in the clause. The clause gives you the arithmetic; Annex F gives you the spread, and the spread is the economics. The data itself flows from CFE to CENACE through CFE Intermediación de Contratos Legados, S.A. de C.V.

The shield can end early. Transitorio CUARTO terminates it if you do not complete every stage, if your assets are granted enabled status in the physical asset registry, or if you begin operating in the Wholesale Electricity Market. In every case, no later than October 6, 2028.

And the expedited route carries real concessions, not just a deadline. Article 5 prohibits the responsible institutions from requiring additional filings or any payment of derechos or aprovechamientos (section II); dispenses with additional interconnection studies and reinforcement works where the legacy figure includes a Contrato Legado (section III); and permits operating plants to add up to fifteen years to the new permit, capped at thirty years total, against a modernisation programme assessed by the CNE (section IV). Plants not yet in operation are capped at twenty-five years.

Not migrating remains lawful. Transitorio SEXTO expressly preserves the rights of holders who do not apply, "por ser de carácter voluntario." What you forfeit is the two-year shield on the charge.

II. If you consume under the scheme

For the industrial operator that holds no permit — the plant that joined a self-supply company as a partner and buys its electricity through it.

The obligation is not yours. The cost may be. The charge falls on the permit holder. Whether it reaches your invoice depends on the pass-through provisions of the agreement you signed. Nothing transfers automatically, and an increase in what the permit holder is billed does not by itself mean you owe the difference.

Now go back to the name. If your pass-through clause covers transmission charges, you are looking at an instrument that bundles distribution, CENACE operation and non-market ancillary services under that label — and, where the plant is renewable or efficient cogeneration, an adjustment-energy payment measured in kilowatt-hours.

Two readings are available: the clause captures whatever the Cargo por el Servicio de Transmisión contains, because that is what the regulation now calls it; or it captures transmission and nothing else. The answer is in your drafting.

The energy component makes the question sharper rather than merely broader. A clause that passes through charges for a service is being asked to carry the shortfall side of the energy bank — a commodity settlement. Those are different risks, they move for different reasons, and a partner who accepted a transmission pass-through years ago was not agreeing to absorb the bank's hourly deficits through a regulated charge the regulator can reprice at will.

The bank is also the reason you joined. If its cost side is being relocated into an instrument outside the contract, the economics that justified the scheme deserve to be recalculated, not assumed.

Ask your permit holder, in writing, before September 18. Only it can make the filings. Four questions:

1. Have you registered the expression of interest under Article 17, section II, stage a)? If not, will you, and when?

2. Will you also submit the migration application in the September 21 – October 16 window? Transitorio TERCERO requires both. One without the other leaves nothing standing.

3. Do the interconnection contract and the Transmission Agreement remain in effect beyond October 6, 2028? That is the other condition, and it is independent of the filings.

4. Which modality under Article 15 will you pursue, and what does it do to the supply I receive?

The fourth is the one people skip. Some modalities change what you are buying, not only what it costs.

You also have two doors of your own, and they are express. Article 5, section XI allows the end users of a self-supply company to aggregate the demand of their load centres in order to request one or more qualified-user registrations. Article 15, section III applies to load centres whose maximum demand — individually or in the aggregate — is one megawatt or more. And Transitorio OCTAVO allows end users to register interest and file on their own where the exclusion of the legacy figures has not been completed.

There is a practical catch. Article 15, section III requires that the Market Participant representing you "debe acreditarse desde la solicitud de migración" — accredited as of the application. If migrating as a qualified user is on the table, the qualified-services supplier has to be chosen and accredited before October 16, not after.

What this alert does not tell you

No number. The formula in numeral 3.2 aggregates four Market Settlement amounts determined per permit holder by CENACE, and the compensated-energy component turns on PEA2ₜ — a price set in Annex F, which we have not seen. Any figure for your increase requires your own settlement data and your own contract. We will not estimate one.

No view on challenge. Voiding the prior framework and redirecting methodology references inside agreements already in force raises a question worth its own analysis. We state no conclusion, and we cite no precedent for a proposition we have not verified in the official source.

What it tells you is that the dates are fixed, that the regulation says they cannot be extended, that there are two of them rather than one, and that the charge is not what its name says it is.

Primary sources

Both published in the Diario Oficial de la Federación of June 18, 2026.

ACUERDO por el que se emiten los Lineamientos para la migración voluntaria y expedita de autoabastecimiento y cogeneración de energía eléctrica a las figuras previstas en la Ley del Sector Eléctrico — Secretaría de Energía

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 — Comisión Nacional de Energía

Which window applies to you, and who has to file it?

Tell us three things: whether you hold the permit or consume under the scheme, whether the plant is renewable or efficient cogeneration, and roughly what your load is. A lawyer will tell you which of the two windows applies to you, who has to file, and what happens if they do not.

A lawyer replies within one business day. Sending this does not create an attorney-client relationship.