What new obligations will suppliers face?
DESNZ’s consultation response to the SSES programme confirms that a new condition will be added to the Electricity Supply Standard Licence Conditions. This will require suppliers to make the necessary data available in line with the TDS set out in the REC.
What is the Tariff Data Specification (TDS)?
The TDS supports greater demand-side flexibility in the UK energy market. By specifying a standard format for how suppliers share tariff data, the TDS will allow Energy Smart Appliances (ESAs) such as communications-enabled Electric Vehicles and heating systems to interact consistently with tariffs across the market. This will help consumers engage in Consumer-Led Flexibility—finding better deals, cutting energy bills, and supporting the UK’s transition to a low-carbon future.
The TDS will include:
- Application Programme Interface (API) specifications: Defining what tariff data must be shared, in what format, and how suppliers must make it available to third parties to enable effective tariff optimisation.
- API Governance: Outlining access rules, usage rules, performance standards, and data compliance requirements to ensure APIs are reliable, secure, and used responsibly.
The Tariff Interoperability project will be led by RECCo in conjunction with DESNZ, working with industry to deliver the TDS.
How will the TDS improve energy management?
As part of the SSES Programme, the TDS supports smarter, efficient energy use by laying the technical and regulatory foundations for a flexible energy system.
The Tariff Interoperability project will standardise tariff data and ensure that ESAs—such as electric vehicle charge points, heat pumps, and batteries—can respond automatically to real-time pricing. This helps shift energy use to cheaper periods, reduces pressure on the grid, and cuts consumer costs. It also creates a more open, innovative environment for new services and market competition.
How and when will changes take effect?
DESNZ and RECCo will work with the industry to introduce requirements for energy suppliers to publish tariff data in a standardised, machine-readable format online. This will drive innovation, empowering third-party intermediaries to develop new services that help consumers better manage their energy use.
The government has outlined provisional timeframes for implementing tariff interoperability, intending to introduce it as soon as possible. During phase two, more complex and less common tariffs will be brought into scope later.
These dates are indicative and may be subject to change:
- Mid to late 2025: A public consultation on proposed minimum viable product (MVP) changes to the REC, expected to run for around two months
- Mid to late 2025: A separate consultation on proposed changes to the Supplier Licence Conditions (SLC), also expected to run for around two months
- Early 2026: Final requirements will be introduced into the REC and SLCs
- Mid to late 2026: Energy suppliers will be required to comply with the new REC and SLC obligations
DESNZ will work with RECCo and industry stakeholders to agree on the exact go-live date for the MVP as part of the delivery phase.
Why is standardising tariff data important?
Energy Smart Appliances (ESAs) need tariff data to optimise energy use, but inconsistent formats create confusion and inefficiencies. Although ESAs collect data from various sources—consumers, smart meters, supplier websites, and comparison sites—the lack of standardisation makes automation difficult.
This forces consumers to configure devices manually or manufacturers to develop costly custom solutions, limiting automation and reducing the benefits of smart energy management.
To address this challenge, the government proposed a common data standard in July 2022. Standardised tariff data will streamline integration, enhance consumer experience, deliver effective demand-side response (DSR), and lower energy system costs.
What does this mean for consumers?
Consumers with one or more ESA will be able to reduce their energy costs by automatically responding to price signals—shifting their usage to periods of lower electricity prices or exporting energy back to the grid during periods of high demand, when the payment received may exceed the cost of replacement energy.
All consumers—including those without an ESA—stand to benefit financially from the wider adoption of ESAs. By enabling greater flexibility in electricity demand, ESAs help reduce the need for additional system capacity, such as backup generation to cover periods when intermittent renewable sources like wind and solar are unavailable. This reduction in infrastructure and operational costs lowers overall system costs, ultimately helping to limit the charges passed on to consumers through their energy bills.
What does this mean for REC Parties?
Energy suppliers will be required to make their tariff data available through APIs in a uniform, standardised format. Each supplier must develop and maintain its API according to the defined schema, ensuring reliable access for ESAs and other systems.
How can stakeholders participate?
Suppliers, industry stakeholders, and technology providers are encouraged to contribute by engaging with consultations, offering feedback, and preparing for implementation.
To take part, stakeholders are invited to join the Tariff Interoperability Working Group (TIWG) to help shape the project’s direction. To express interest, please get in touch with the REC Code Manager at enquiries@recmanager.co.uk
Need more information?
- Read the Business Case for Tariff Interoperability
- Read DESNZ’s consultation response to the SSES Programme
- Stay updated through the REC Code Manager’s weekly REC Bulletin
