Successful delivery of REC Changes to support MHHS go-live

We’re pleased to confirm that we’ve successfully delivered the changes needed to support the Market-wide Half-Hourly Settlement (MHHS) Go-Live milestone.

This marks the culmination of more than three years of collaboration with the MHHS Programme and industry colleagues. We’ve made sure Retail Energy Code (REC) systems, processes, and governance are ready to underpin this fundamental market reform.

What we’ve delivered

M8: Code & Central Systems Readiness
  • Implemented REC Changes
  • Updated Category 3 products and guidance documents
  • Launched the new Meter Configuration Table
  • Sent Data Transfer Network updates to ElectraLink
M10: Go-Live Readiness
  • Deployed changes to the Electricity Enquiry Service
  • Qualified Milestone 10-ready REC Parties
  • Received Management Assertions on readiness from REC Parties
  • Completed internal operational readiness and training

Why this matters

Market-wide Half-Hourly Settlement is a major reform stemming from Ofgem’s Electricity Settlement Reform Significant Code Review (SCR). It introduces the Target Operating Model (TOM), which restructures market roles, enhances data processing, and mandates industry-wide compliance to support Great Britain’s transition to a smarter, low-carbon energy system.

MHHS will:
  • Make the true cost of electricity supply clearer
  • Enable near real-time price signals to market participants
  • Support innovative tariffs and competitive services for consumers
  • Reduce the need for costly grid balancing and infrastructure upgrades

These reforms are transformative. They fundamentally change how the electricity market operates and are driving the move towards a smarter, more flexible energy system.

What’s next

REC Parties will continue to qualify in phases over the next year, with migration starting next month and running for around 18 months. Once the industry fully transitions to MHHS, further REC Changes will follow to remove redundant arrangements.

Key upcoming milestones include:
  1. M15: Migration Complete when all customers’ MPANs are settled half-hourly (target May 2027)
  2. M16: Cutover when the new MHHS settlement timetable goes live (target July 2027)

We’ll also participate in the early life support phase to support the stability of these changes.

Find out more

We’re here to help

If you have any further questions or need additional support, please reach out to us at mhhs@retailenergycode.co.uk.

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