What Is RIIO-3? UK Energy Network Framework Explained
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Quick Answer: RIIO-3 is Ofgem’s latest five-year price control framework for Great Britain’s gas distribution, gas transmission and electricity transmission networks. It runs from 1 April 2026 to 31 March 2031 and sets the revenue these monopoly network operators can earn, the outputs they must deliver and the incentives or penalties attached to performance. In practice, RIIO-3 is designed to balance investment, resilience, decarbonisation, consumer value and accountability across the energy networks that keep power and gas flowing to homes and businesses. The structure of this post follows the headers in your attached document.
What does RIIO stand for?
RIIO stands for Revenues = Incentives + Innovation + Outputs. That formula captures the logic behind Ofgem’s network regulation model. Rather than simply allowing network companies to recover costs, the framework sets allowed revenues, linking part of those revenues to performance incentives. It was designed to support innovation that creates consumer value, based on companies delivering specific outputs such as reliability, safety, resilience, environmental performance, and customer service.
In other words, RIIO is not just about how much networks can charge. It is about measurable impacts that they must deliver in return for that income, proving value for money and how they push themselves to improve over time. That is why RIIO matters well beyond the energy sector itself. For businesses, it influences long-term infrastructure quality, connection timelines, data transparency and, indirectly, network-related costs that feed into bills and investment decisions.
What Is RIIO-3? The framework explained
RIIO-3 is the third generation of this regulatory model for the relevant network sectors. For this cycle, Ofgem has applied the framework to electricity transmission, gas transmission and gas distribution. The price control period runs from 1 April 2026 to 31 March 2031, lasting five years. Ofgem’s role is to decide what efficient spending is justified, the outputs network companies must meet and how returns should be calibrated so consumers are protected while essential infrastructure continues to be maintained and upgraded.
The framework sits at the centre of a difficult balancing act. Britain needs safe, dependable networks that are flexible enough to support net-zero ambitions, changing patterns of electricity demand, new infrastructure projects and a more digital energy system. RIIO-3 is more than a finance exercise. It is a delivery framework for the next phase of network transformation.
What is the RIIO-3 draft determination?
The RIIO-3 Draft Determination is Ofgem’s provisional regulatory decision on how the next control period should work before final decisions are locked in. It follows the review of company business plans and precedes the final settlement.
Draft determination is not the finished rulebook, but it is still highly significant. It signals regulatory direction, highlights areas where spending claims may be cut or reshaped, and gives businesses, investors, contractors and market participants an early view of likely priorities for the coming control period.
What does the draft determination cover?
As stated above, the RIIO-3 Draft Determinations were Ofgem’s consultation decisions following its review of the business plans submitted by network companies in December 2024. The consultation package covered:
- The overall framework
- Proposed allowance
- Sector-specific positions
- Finance assumptions
- Output measures
- Incentive design
- Company-level proposals for the affected networks.
It was the point where Ofgem set out its provisional view on what it thought companies should be funded to do and how performance should be judged, with feedback from networks and stakeholders.
Draft determinations are significant because they mark the point at which the framework becomes concrete. They show which proposed investments regulators support, which assumptions they challenge, what consumer protections are being tightened and where companies may face stronger incentives or greater scrutiny. They must be staunchly reviewed before any final settlement is made.
When was the RIIO-3 draft determination published?
Ofgem published the RIIO-3 Draft Determinations on 1 July 2025. The consultation then ran until 26 August 2025. Final Determinations followed on 4 December 2025, ahead of the framework going live on 1 April 2026.
Which networks and companies does RIIO-3 apply to?
RIIO-3 applies to three parts of Great Britain’s energy network system: electricity transmission, gas transmission and gas distribution. It does not cover electricity distribution for the same timeline, because electricity distribution moves onto a different control period later. Ofgem’s own overview of current price controls makes that distinction clear.
In electricity transmission, RIIO-3 applies to the transmission owners, including:
- National Grid Electricity Transmission
- Scottish Power Transmission
- Scottish Hydro Electric Transmission
As reflected in Ofgem’s consultation and determination annexes. In gas transmission, the framework applies to National Gas, which operates the National Transmission System. In gas distribution, the regulated companies include:
For a business audience, the important point is simple. RIIO-3 governs the strategic network businesses that transport electricity at the transmission level and move gas through the national and regional gas systems. These companies are natural monopolies, so competitive market discipline is limited. Regulation is vital to protect customers and set expectations.
How is RIIO-3 different from RIIO-2?
RIIO-3 builds on the same core logic as RIIO-2, but operates in a more urgent system context. Electricity demand growth, grid reinforcement needs, security concerns, decarbonisation pressures and digital expectations are all more pronounced now than when RIIO-2 was set. As a result, RIIO-3 places a stronger emphasis on enabling the low-cost energy transition, sharpening output delivery, improving accountability and making data and governance more usable for wider stakeholders.
A practical comparison looks like this:
| Area | RIIO-2 | RIIO-3 |
| Period | Current control for relevant sectors ended 31 March 2026 | Runs 1 April 2026 to 31 March 2031 |
| Policy context | Strong focus on efficiency and consumer value | Greater urgency around transition, resilience and infrastructure readiness |
| Network scope | Gas distribution, gas transmission and electricity transmission under the previous cycle | Same core sectors for 2026 to 2031, with electricity distribution on a different timeline |
| Outputs and incentives | Established RIIO model with sector incentives | Refined outputs, stronger delivery focus and updated incentive design |
| Data and transparency | Ongoing digitalisation expectations | Wider push toward more open and accessible data, including presumed open principles in some areas |
What are the core outputs RIIO-3 requires networks to deliver?
At a high level, Ofgem’s RIIO model continues to focus on outputs such as safety, environmental protection, customer satisfaction, social obligations, network connections, reliability and availability. In RIIO-3, those themes remain central, but they are framed more clearly against resilience needs, asset health, consumer protection and the demands of decarbonisation.
Key output categories
Key categories under RIIO-3 include:
- Network reliability and resilience
- Environmental performance
- Stakeholder and consumer outcomes
- Delivery of strategic infrastructure or system capabilities
In electricity transmission, for example, Ofgem has used output delivery incentives connected to major projects and connections. In the cross-sector overview, Ofgem also highlights environmental impact mitigation and ongoing resilience and asset health as common output areas.
What that means in plain English is that networks are not only being funded to keep the lights on or gas moving. They are being judged on whether they maintain resilient assets, support future system change, handle customer and stakeholder obligations properly, and deliver projects in ways that reflect consumer interests.
What does RIIO-3 mean for the UK gas sector specifically?
For the UK gas sector, RIIO-3 is especially important because it comes at a time of global uncertainty and transition. Gas networks still play a major role in energy security and business operations, but they are also under increasing pressure to align with various goals. Handling decarbonisation targets, methane reduction expectations, improved data handling and tougher ‘value for money’ scrutiny at once isn’t easy. RIIO-3 becomes the framework through which Ofgem manages that tension.
Decarbonisation and the energy transition
Ofgem’s RIIO-3 material explicitly connects the framework to decarbonising the energy system. For gas, that does not mean an overnight shift away from the sector. It means the regulator expects network planning and investment to be justified in the context of the wider energy transition, future demand uncertainty, resilience and consumer value. Networks need to maintain safe, dependable service while demonstrating that spending aligns with a changing system rather than legacy assumptions.
The “presumed open” data principle
A major direction of travel in RIIO-3 is better data transparency and usability. The broader framework and guidance emphasise a more open, accessible approach to information so stakeholders can scrutinise performance, understand network plans and engage with delivery more effectively. The phrase “presumed open” captures that expectation that data should be shared unless there is a clear reason not to. For businesses, consultants and market participants, that can mean improved visibility into network activity and decision-making.
Penalties for non-compliance
RIIO-3 is not a soft guidance exercise. Incentives and penalties remain central to the model. Ofgem’s RIIO-3 documents describe asymmetric penalties, late-delivery consequences, and financial output delivery incentives, under which companies can lose money for underperformance and, in some cases, earn rewards for early or on-time delivery. In electricity transmission, the Major Projects ODI-F is a clear example, with penalties applying when significant projects are delivered late. Gas distribution determinations also discuss penalties linked to specific outcomes and under-delivery risk.
What does RIIO-3 mean for business energy costs?
RIIO-3 does not set the price of a business’s retail energy contract. However, it does influence the regulated network costs that flow through the energy system and ultimately to bills. The key business question is not simply whether costs go up or down in one year. It is whether the framework delivers efficient long-term investment, avoids waste, reduces delays, supports system resilience and prevents more expensive problems later.
So while some network investment can add cost pressure in the short term, Ofgem’s approach is based on the idea that timely, efficient infrastructure spending should support reliability, security of supply and the energy transition at lower whole-system cost over time. For larger energy users, developers and multi-site businesses, the operational implications can be just as important as the direct cost implications.
How should businesses and energy professionals prepare for RIIO-3?
For business energy buyers
Business energy buyers should treat RIIO-3 as a strategic market framework rather than a niche regulatory topic. It is worth monitoring how network investment priorities, resilience obligations and project delivery incentives may affect regional infrastructure, future connection options and longer-term cost pass-through. Businesses with high-demand sites, expansion plans or on-site generation ambitions should pay particular attention to developments in transmission and network capacity.
For energy professionals and contractors
For consultants, contractors, developers, and sector specialists, RIIO-3 provides a clearer signal on where regulated network activity will be focused between 2026 and 2031. That includes resilience, asset health, environmental delivery, major infrastructure and system readiness. The best preparation is to understand the framework, follow Ofgem guidance and keep track of how network companies translate final determinations into delivery plans.
If you found this article helpful and want to learn more about the business energy sector, visit the D-ENERGi blog today. We have a massive archive of resources, just like this one, covering market shifts as well as long-term topics related to energy use and efficiency. Staying informed is the best way to navigate the seas in today’s uncertain market.
Frequently Asked Questions
What does RIIO stand for in energy?
It stands for Revenues = Incentives + Innovation + Outputs. It is Ofgem’s model for regulating monopoly gas and electricity networks.
When does RIIO-3 start and end?
RIIO-3 runs from 1 April 2026 to 31 March 2031.
Who regulates RIIO-3?
RIIO-3 is regulated by Ofgem, the energy regulator for Great Britain.
How does RIIO-3 affect energy bills for businesses?
It affects the regulated network cost element within the wider energy system rather than directly setting a retail contract rate. Its main influence is through allowed network revenues, investment decisions and delivery incentives.
What is new in RIIO-3 compared to RIIO-2?
The biggest shifts are a stronger emphasis on enabling the energy transition, sharper output accountability, updated incentive structures and a more explicit focus on resilience, asset health and better data transparency.
