From Profile to Precision: Pricing the MHHS Transition into Your 2026 Electricity Renewal

Most UK electricity buyers have spent the past few years learning to read a bill more closely. Fewer have had to think about how the electricity they use is settled behind the scenes. That is about to change. Ofgem's Market-wide Half-Hourly Settlement (MHHS) programme is not simply a metering upgrade. It is a redesign of the data flows, settlement timetable and risk allocation that sit underneath every business electricity contract. For organisations renewing in 2026, the practical question is not whether MHHS is relevant. It is whether the price on the table already reflects the transition.

Why non-half-hourly sites are affected

It is tempting to assume MHHS only matters if you already receive half-hourly data. That assumption is now out of date. The programme moves the whole electricity market away from profile-based settlement — where consumption for smaller sites is estimated using standard profiles — towards half-hourly settlement for all meter points. The rollout relies on smart and advanced meter data, routed through new market systems, including the Data Integration Platform, and on suppliers, agents and settlement bodies being ready to process far greater volumes of interval data.

For a business with a portfolio of smaller sites, the change may be invisible on the face of the bill. It will not be invisible in the contract. Suppliers will carry different forecasting, reconciliation and data-quality risks during the migration. Those risks have a cost, and procurement teams should expect to see them reflected — explicitly or implicitly — in renewals that span the transition.

The migration timetable and the renewal calendar

The MHHS programme has already been through a significant reset. The original timetable was revised, and the market is now working to a staged migration running through 2026 and into a revised go-live in 2027. For buyers, the important point is not the precise date of any single milestone. It is that contracts signed this year will almost certainly operate across the cutover.

That creates a timing problem. A renewal agreed in late 2026 may run well into the new settlement arrangements. If the supplier has priced transition risk conservatively, the buyer may be paying for uncertainty that could have been clarified. If the supplier has priced it too thinly, the buyer may face reconciliation adjustments or service issues later. Either way, the renewal is the moment to test the supplier's readiness rather than accept a single blended rate with no explanation.

Where transition risk appears in a 2026 offer

Suppliers are unlikely to label a line item 'MHHS risk'. The cost may be embedded in the unit rate, in standing charges, in a data-services fee, or in revised tolerance and reconciliation terms. It may also appear as a pass-through clause covering settlement adjustments or additional data-processing costs.

None of that is automatically unreasonable. Migration involves real cost: system changes, testing, data cleansing and additional operational resource. The procurement issue is transparency. A supplier that can explain how it has treated transition risk is easier to compare with one that cannot. Buyers should ask whether the offer assumes a particular migration date, whether it includes any transition-related service charges, and how reconciliation will work if data quality is poor during the switch.

Contract clauses worth testing before signature

Several terms deserve closer attention in 2026 renewals. Data access is the first. Confirm what interval data the supplier will provide, in what format, and at what frequency. If you intend to use half-hourly data for internal reporting or flexibility decisions, make sure the contract does not restrict it.

Second, look at service levels for data retrieval and estimated reads. During migration, missing or late data is a realistic risk. The contract should set out who is responsible for resolving gaps and how any resulting settlement adjustments are handled.

Third, check change-control provisions. If MHHS-related costs arise after signature, can the supplier pass them through automatically, or is there a defined process for evidence and agreement? Fourth, review exit and transfer arrangements. If the contract ends during or shortly after migration, the handover of data and meter details should be clear.

A procurement checklist for 2026 renewals

• Ask each supplier for its MHHS migration plan and its current readiness position.
• Confirm whether the meter estate is smart or advanced-meter capable, and identify any sites likely to need remedial work.
• Map contract end dates against the migration window and consider whether a shorter term or break clause would reduce exposure.
• Request a breakdown of any transition-related charges, including data services and reconciliation provisions.
• Check that interval data will be available to your organisation, not just to the supplier.
• Test the supplier's approach to estimated reads, missing data and post-migration adjustments.
• Compare offers on the treatment of transition risk, not only on headline unit rates.

MHHS should, in time, produce more accurate settlement and better foundations for flexibility and demand-side response. Those are genuine benefits for cost-conscious businesses. But the transition itself introduces a period of pricing ambiguity. The organisations that manage it best will treat MHHS as a procurement issue, not a technical curiosity — and will make suppliers show their working before signing a 2026 renewal.