Market-wide Half-Hourly Settlement
(MHHS) Programme

 

Market-wide Half-Hourly Settlement (MHHS) Programme - Update Feb 2026

 

Progress, Supplier Migration and What Businesses Need to Know in 2026

​

Market-wide Half-Hourly Settlement (MHHS) has now moved firmly into its implementation phase, with electricity suppliers actively migrating meters across Great Britain. As the programme progresses through 2026, MHHS is transitioning from a regulatory reform into an operational change that will reshape how electricity consumption is measured, settled, and increasingly valued within the market.

For most businesses, the change itself happens behind the scenes. However, the increased use of half-hourly data is already changing how energy costs are understood, how portfolios are analysed, and how suppliers structure future energy products.

​

What is Market-wide Half-Hourly Settlement?

 

MHHS is an Ofgem-led reform designed to modernise electricity settlement by replacing estimated consumption profiles with actual half-hourly meter data wherever possible.Historically, most electricity consumption has been settled using industry profiles rather than real usage patterns. MHHS aligns settlement with when energy is actually consumed, enabling suppliers to purchase energy more accurately and supporting a more flexible electricity system. Central MHHS systems went live in 2025, allowing suppliers to begin migrating meters into the new arrangements while legacy settlement continues to operate in parallel during transition

​

MHHS Timeline and Current Programme Status

​

The programme is now progressing through its migration window, with key milestones remaining unchanged:

​

• October 2025 – Supplier migration to half-hourly settlement begins

• 2025–2027 – Industry-wide migration period

• October 2026 (Milestone 14) – All suppliers required to be qualified to operate under MHHS

• May 2027 (Milestone 15) – Completion of migration to half-hourly settlement

• July 2027 (Milestone 16) – Cutover to the new, faster settlement timetable

 

The migration phase runs for approximately 18 months, during which both legacy and MHHS settlement arrangements operate side by side to maintain market stability.

 

Progress is already visible. Industry expectations remain that around 80% of meters will have migrated by October 2026, making 2026 the most active delivery year of the programme.

​

How Suppliers Are Being Progressed Through MHHS Migration

​

One of the most common questions across the market is which suppliers are migrating and when. Unlike many industry programmes, MHHS does not publish a supplier-by-supplier timetable. Instead, supplier progression follows a qualification-led model.

​

Qualification before migration

​

Suppliers must complete MHHS qualification before they can migrate customers into the new arrangements. Qualification confirms that systems, processes, and data flows can operate within the new Target Operating Model.The programme has structured qualification activity into waves, with testing and assessment windows running through 2025 and 2026 before suppliers can begin migration activity. Suppliers that participated in earlier system integration testing were able to begin migration from the start of the migration window, while others progress once qualification is complete and migration capacity is available.

​

Migration capacity and scheduling

 

Migration is centrally coordinated through the MHHS Migration Control Centre. This ensures migration activity is delivered fairly and within system capacity limits rather than allowing all suppliers to migrate simultaneously.

To manage delivery, migration is organised into structured “sprints”, each including planning, execution and review phases.

 

This means:

​

• Suppliers begin migration at different points depending on qualification readiness

• Even within a single supplier portfolio, sites may migrate at different times

• Migration volumes are controlled to maintain industry stability

 

From a customer perspective, this explains why businesses with the same supplier may see sites move to MHHS months apart.

​

A regulatory incentive to progress

​

The programme also includes incentives to ensure suppliers progress on time. Suppliers that have not qualified by Milestone 14 risk restrictions on registering new customers until qualification is complete, creating a strong commercial driver for progression during 2026.

​

Why MHHS Matters Beyond Compliance

​

Although MHHS is primarily a settlement reform, the practical impact for businesses sits in how electricity consumption becomes more transparent within pricing and analysis.

 

Key changes include:

 

1. Settlement aligned with actual consumption

2. Energy is settled based on when electricity is used rather than assumed usage profiles, increasing accuracy but also exposing demand patterns more clearly.

3. Greater emphasis on data quality

4. As settlement becomes more granular, inaccurate meter data or inconsistent portfolio information becomes more visible.

5. Stronger flexibility signals in pricing

6. Half-hourly settlement supports time-of-use tariffs and demand flexibility services, encouraging consumption to move away from peak periods.

​

The Operational Impact for Multi-Site Businesses

​

For many organisations, MHHS will not immediately change contract structures or billing formats. The more significant change is the increasing importance of data visibility.

 

As settlement moves fully to half-hourly data:

• Consumption patterns become easier to compare across sites

• Portfolio anomalies become more visible

• Billing reconciliation relies more heavily on accurate data flows

• Energy costs become more closely linked to operational behaviour

 

This continues a wider market shift away from energy management focused solely on unit rates toward strategies informed by usage patterns and demand behaviour.

​

MHHS and the Future Electricity Market

​

MHHS forms part of a broader transition toward a more flexible and data-driven electricity system. By aligning settlement with real demand, the programme supports:

• Faster and more accurate settlement cycles

• Greater integration of renewable generation

• Development of flexibility markets

• Improved system forecasting and balancing

 

The reduction of the settlement timetable from around 14 months to four months by July 2027 represents a significant structural change in how quickly market costs are reconciled.

​

What Businesses Should Be Doing Now

​

Migration itself is managed by suppliers, but the transition period presents an opportunity for businesses to prepare operationally.

 

Organisations best positioned to benefit from MHHS typically:

• Maintain accurate and validated meter data

• Have visibility of half-hourly consumption across their portfolio

• Understand site-level demand behaviour

• Use consumption insight to inform procurement and operational decisions

 

MHHS does not immediately increase energy costs, but it increases transparency. As settlement becomes faster and more data-driven, the ability to interpret consumption data becomes increasingly valuable.

​

Looking Ahead

​

With supplier migration accelerating through 2026, MHHS is no longer a future reform but an active market transition. The next phase for businesses is less about readiness and more about optimisation, ensuring that increased data availability translates into improved cost control, operational insight, and long-term energy strategy.

​