By Taylor Adriano Chaves
The free energy market has existed in Brazil since 1998, when ANEEL Resolution 265 defined the rules for trading and allowed a handful of large industries to choose their supplier. Since then, the access threshold has been lowered by demand brackets, always by regulatory decision.
Law 15.269, of November 24, 2025, did something different. It legally established the date when the gate falls for everyone.
However, the agency is still responsible for the opening. And what they need to deliver beforehand is longer than the headline suggested.
The opening of the low-voltage market means extending to consumers served at voltages below 2,3 kV, the so-called Group B, the possibility of contracting energy directly in the Free Contracting Environment, negotiating price, term, volume and source with trading companies and generators instead of buying from the local distributor. This milestone came with the conversion of Provisional Measure 1.304/2025 into Law 15.269/2025, published in the Official Gazette of the Union on November 25, 2025.
The schedule has a date, and it has a condition.
The law establishes two phases. Low-voltage commercial and industrial consumers can migrate within 24 months of its entry into force. Others, including residential and rural consumers, have up to 36 months.
Translated into the calendar, this places the first window in November 2027 and the full opening in November 2028.
This is where the distinction between those who plan and those who merely observe comes in. These deadlines are ceilings, not triggers. The law itself makes opening conditional on meeting prior requirements, and these are not mere formalities.
The list includes a communication plan for consumers, definition of tariffs applicable to the free and regulated markets, regulation of last resort supply, creation of a standard product with a reference price, and rules to address over-contracting or unintentional exposure of distributors.
Each of these items is a regulatory process involving public consultation, impact analysis, and disputes between stakeholders with opposing interests. None of them can be resolved in a single board meeting.
It is worth noting why the law chose this design. Setting a deadline without conditions would create an opening on top of an unprepared system, risking a contractual blackout. Setting only conditions, without a deadline, would repeat the history of the previous two decades, in which the frontier advanced slowly and by discretionary decision. The text attempted a middle ground, and it is in this middle ground that the dispute will take place.
The ultimate supply sustains the rest.
Among the requirements, the Supplier of Last Resort is the one that most influences the rest, and it is also the least discussed outside the industry.
The function is simple to state. If the energy supplier serving a consumer in the free market terminates the contract, breaks it, or ceases to represent them in the trading chamber, someone needs to continue supplying energy the following day. The law created this figure and assigned regulation and oversight to ANEEL (Brazilian Electricity Regulatory Agency).
The difficulty lies in the calculation. A continuity mechanism costs money because it requires contracting for reserve energy or exposure to short-term prices during times of stress. Determining who pays this cost is a distributive, not a technical, decision.
With large consumers, the problem is manageable because there are few of them and they have the infrastructure to handle it themselves. With millions of low-voltage units, the scale changes the nature of the design.
Until that rule is in place, there's no way to open the door with operational safety. That's why the legal deadline and the actual deadline may not coincide.
Standard product and the asymmetry that no one can ignore.
Consumers who switch to the ACL (Free Contracting Environment) today have an energy department, a contracted consultant, or at least someone who understands the load curve.
The baker on the corner doesn't have it. And he's the one who reaches the first stage.
The law addresses this with a standard product, an offer with a reference price that allows for direct comparison between proposals, and with educational campaigns coordinated by the agency. The logic is to create a public anchor against which the consumer can measure what is being offered.
Anyone who follows retail markets open to consumers in other countries knows that this is the phase with the greatest reputational risk. Aggressive sales tactics, contracts with poorly explained loyalty clauses, and disproportionate termination fees are classic examples of the transition period, and the damage affects the credibility of the entire model.
There is a second, less obvious component of asymmetry. The low-voltage consumer who migrates assumes price risk in a market where the short-term price fluctuates with hydrology and thermal dispatch. A standard product resolves the comparison between offers, but not the exposure to the risk embedded in each one.
For the trading companies, this means that the discussion about commercial conduct standards will come before the opening, not after. For the distributors, it means that the relationship with the remaining captive consumer changes in nature, because those who stay become, to some extent, those who did not have the information to leave.
The CDE allocation changes the account before any migration.
There is an effect of the law that is already in effect in 2026 and that affects those who do not intend to migrate at all.
The Energy Development Account finances sectoral subsidies and is distributed among consumers. Law 15.269 adjusted this distribution, altering the relative share of voltage levels and reducing the weight on high and medium voltage.
The law also stipulated a charge applicable when subsidies exceed the annual account ceiling, with payment attributed to the agents that generate the excess. It is a containment mechanism, and the calculation formula depends on regulation.
The practical point for the industrial consumer is straightforward. Part of the expected gain from the migration could be neutralized, or amplified, by how the agency defines these methodologies in future tariff reviews.
Projections of savings made today using yesterday's cost structure have a short shelf life.
A methodological warning closes the CDE block. Comparing regulated tariffs and prices in the free market only makes sense when both sides include charges, taxes, and management costs. Comparing energy prices against full tariffs produces the nice number that appears in commercial presentations and disappears at the first month-end closing.
Storage has entered the legal framework.
One aspect of the law is often left out of the summary but is worth noting because it changes the investment decision matrix.
The text officially recognizes energy storage as part of the national electrical infrastructure. Batteries and equivalent technologies will now have a regulatory framework, with the possibility of tax incentives and inclusion in the special incentive regime for infrastructure.
The technical rules and contracting models will be detailed later. But legal recognition is what allows structuring the project, obtaining financing, and discussing remuneration for an asset that until now had no clear place in Brazilian regulation.
For those operating in the free market, storage and contractual flexibility are essentially the same thing. Those who can shift consumption tend to negotiate better deals.
The magnitude of what is at stake.
It's worthwhile to assess the existing market before projecting what's to come.
Data from the Chamber of Electric Energy Commercialization indicates that the free market already accounts for approximately 43% of all energy consumed in the National Interconnected System, bringing together approximately 85 consumers by the end of 2025. This growth resulted from the progressive reduction of demand limits and the advancement of retail trading.
Low voltage is a whole different order of magnitude. It involves millions of consumer units with small, dispersed consumption patterns that are sensitive to price.
The difference in profile also has an operational effect. Serving a large consumer involves a negotiated contract, dedicated metering, and a direct relationship. Serving hundreds of thousands of small consumers requires a platform, automated registration, and a scalable billing process, something closer to telecommunications than to the traditional energy market.
Market estimates suggest potential savings of up to 18% on the portion of energy purchases. This is an estimate and varies according to consumption profile, region, contractual strategy, and market conditions at the time of contracting. Treating this number as a promise is the mistake the sector needs to avoid in its communication with the end consumer.
What to watch out for between now and the first window.
ANEEL's regulatory agenda becomes the most important document for those working in the sector, even more so than the text of the law.
Each public consultation on pricing, standard products, last resort supply, or over-contracting treatment defines a part of the final design. Those who participate in the consultation influence the rule. Those who read it later simply adapt.
Distributors need to map their contractual exposure because losing volume without adjusting their purchasing portfolio leads to costly over-contracting. Trading companies need to design operations to handle a high volume of small contracts, which is a problem of technology and acquisition costs, not a legal argument.
There is also portfolio work that needs to begin ahead of schedule. Purchase agreements signed today by distributors cover periods when some of the load may have already shifted, and the flexibility of these acquisitions is what separates manageable exposure from losses passed on to the tariff.
And the low-voltage commercial consumer, first in line, has about a year to understand the difference between the tariff they pay today and the total cost of being in the free market.
Why is regulatory competence now the decisive factor?
The transition of the Brazilian electricity sector is no longer a matter for those who read the law, but now requires a combined understanding of regulations, tariffs, and the market.
A lawyer who is well-versed in the legal framework but doesn't know how to interpret a tariff structure cannot assess whether migration is worthwhile. An analyst who is knowledgeable about pricing but unfamiliar with the design of charges projects savings that the tariff review dismantles.
The IDP Executive MBA in Law and Regulation of the Electricity Sector works on these two fronts. The first axis covers the legal and institutional frameworks, the role of ANEEL (Brazilian Electricity Regulatory Agency), administrative contracts, auctions, and concessions. The second addresses commercialization in regulated and free environments, pricing, market risks, distributed generation, and digitalization.
The course features live classes held every two weeks, and the faculty includes Agnes Costa, director of ANEEL since 2022, Rodrigo Limp, Secretary of Electric Energy at the Ministry of Mines and Energy, and Leandro Caixeta, Superintendent of Tariff Management and Economic Regulation.
Learn more about the MBA in Law and Regulation of the Electricity Sector: https://pos.idp.edu.br/products/mba-em-direito-e-regulacao-do-setor-eletrico
References
Legal framework, sanction date 11/24/2025 and publication date 11/25/2025, conversion of Provisional Measure 1.304/2025 which incorporated provisions of Provisional Measure 1.300: https://coprelenergia.com.br/abertura-total-do-mercado-livre-de-energia-o-que-deve-acontecer-nos-proximos-tres-anos-a-partir-da-lei-15-269-25/
Definition of low voltage as voltage below 2,3 kV, 24- and 36-month timeline, and creation of the SUI regulated and supervised by ANEEL: https://clarke.com.br/post/reforma-no-setor-eletrico/
Conditions for opening the market, including communication plan, definition of tariffs for both environments, regulation of last resort supply, standard product, and handling of over-contracting or involuntary exposure of distributors: https://www.luxenergia.com.br/post/abertura-mercado-livre-energia-2026-cronograma-empresas
Adjustment of the CDE allocation starting in 2026, charge applicable when subsidies exceed the annual ceiling, recognition of storage as infrastructure and possibility of inclusion in REIDI, in addition to dependence on regulation by ANEEL and MME: https://echoenergia.com.br/blog/lei-15-269-2025-novo-marco-setor-eletrico/ and https://echoenergia.com.br/blog/mercado-livre-energia-lei-15-269-2025/
The ACL (Free Contracting Environment) will account for approximately 43% of the energy consumed in the SIN (National Interconnected System) and will serve approximately 85 consumers by the end of 2025, according to CCEE (Brazilian Chamber of Electric Energy Commercialization), with an estimated savings of up to 18% on the energy purchase portion: https://cenarioenergia.com.br/2026/07/08/abertura-da-baixa-tensao-inaugura-nova-era-do-mercado-livre-e-pode-reduzir-conta-de-luz-em-ate-18/
History of ANEEL Resolution 265, of August 13, 1998, as the initial milestone for commercialization, on the official page of the Ministry of Mines and Energy: https://www.gov.br/mme/pt-br/a-revolucao-brasileira-em-energia-e-mineracao/energia-eletrica/reforma-do-setor-eletrico-e-abertura-do-mercado-de-energia
