Milestone Updates

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M11 and M12 approved

At the Extraordinary Programme Steering Group (ePSG) meeting on Tuesday 21 October 2025, the Senior Responsible Owner (SRO) approved two key milestones: 

  • Milestone 11 (M11): Commencement of the 18-month migration period for Unmetered Supplies (UMS) and Advanced Metered Meter Point Administration Numbers (MPANs) 
  • Milestone 12 (M12): Commencement of the 18-month migration period for Smart and Non-Smart Metered MPANs

The approval of M11 and M12 marks the formal start of the industry-wide migration phase. Programme participants will now begin migrating customers to the new MHHS arrangements, with activities coordinated through the Migration Control Centre (MCC) and monitored through established Programme governance structures. 

This milestone represents a pivotal moment for the Programme, as we collectively progress toward full migration completion at Milestone 15 (M15) and transition to new settlement arrangements at Milestone 16 (M16). 

The Programme will continue to share updates through The Clock and across governance forums as we move decisively into the next phase of delivery. 

M10 and M13 approved

At the Extraordinary Programme Steering Group (ePSG) meeting on Wednesday 24 September 2025, the Senior Responsible Owner (SRO) approved two key milestones: 

  • Milestone 10 (M10): Central systems ready to migrate Meter Point Administration Numbers (MPANs) 
  • Milestone 13 (M13): Load Shaping System (LSS) switched on 

This approval marks a significant step towards full Market-wide Half-Hourly Settlement (MHHS) implementation and follows the successful transition of Central Services and Licensed Distribution System Operators (LDSOs) in line with the M10/M11 Cutover Plan. 

The Programme extends its thanks to the Systems Integration Testing (SIT) participants, Central Parties and Core Capability Providers, Code Bodies, Representatives for industry meetings, Ofgem Programme Sponsors for their ongoing support and engagement, and finally the MHHS Programme Lead Delivery Partner (LDP) Team and SRO Team in reaching this milestone. 

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Code changes (M8) published 

The Programme is also pleased to confirm that Milestone 8 (M8) the delivery of Code changes has been published by the Balancing & Settlement Company (BSC), Retail Energy Code Company (RECCo), and the Distribution Connection and Use of System Agreement (DCUSA).

This codification of the MHHS Target Operating Model (TOM) and Design establishes the legal baseline for the new MHHS arrangements. 

If you have any questions, please email the Programme Party Coordinator (PPC) team at PPC@mhhsprogramme.co.uk