M14 – All suppliers must be able to access MPANs under the new Target Operating Model (TOM) 

• Milestone Completion Date: 28 October 2026 

Milestone 14 (M14) marks the point in the Market-wide Half-Hourly Settlement (MHHS) migration period when all Suppliers must have the systems and services in place to accept Meter Point Administration Number (MPANs) under the new MHHS Target Operating Model (TOM). 

All Suppliers must be MHHS Qualified and Service Active, to comply with this milestone. For more information, please visit the Qualification Approval Process page of this website.

From M14 onwards, MPANs cannot be moved back into the Non-Half-Hourly (NHH) regime on change of supplier (i.e. reverse migration ceases). Any Supplier that has not put the required arrangements in place will lose the ability to take on new customers / new MPANs until they are compliant as set out in the Qualification Approach & Plan: Annex 4. 

Progress towards M14 is being actively monitored by the Qualification Advisory Group (QAG) and other governance groups including the PSG.

For more information on the Qualification process please see the Qualification section of this website. 

M15 – Full transition complete 

• Milestone Completion Date: 07 May 2027 

Milestone 15 (M15) represents completion of implementation activities and the conclusion of the 18-month migration period. 

By M15, all Suppliers must have migrated all MPANs into the new MHHS arrangements, with market completion assessed against the M15 Acceptance Criteria (i.e. ensuring that all MPANs are in the defined “acceptable” end states). Any shortfall against the M15 Acceptance Criteria is expected to be managed and escalated through the MHHS Governance Framework which you can view on the MHHS Programme Governance page of this website.

This milestone is a pivotal point for the Programme as we move from migration execution into final readiness for the settlement timetable transition at Milestone 16 (M16). 

The Migration & Cutover Advisory Group (MCAG) is actively monitoring progress towards M15. 

For more information on the Migration process please see the Migration section of this website. 

M16 – Cutover to the new settlement timetable 

• Milestone Completion Date: 2 July 2027 

Milestone 16 (M16) is the Settlement Timetable Transition, the point at which the market cuts over from the legacy 14-month settlement timetable to the new four-month settlement timetable, aligned to the MHHS TOM. 

M16 is expected to take place following a stabilisation period after migration completion, enabling the market to transition to the new, faster settlement timetable once MHHS arrangements are operating steadily. 

The process and timings for the transition to the new Settlement Timetable are set out in the Requirements for the Transition to the new MHHS Settlement Timetable with a worked example of the revised Settlement Timetable provided here. 

The Programme will continue to share updates through The Clock and governance forums as we approach M16 and prepare for the transition to the new settlement timetable. 

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

Approval of M11 and M12 marked the formal start of the industry-wide migration phase. Programme participants are 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 represented a pivotal moment for the Programme, as we continue to progress towards full migration completion at Milestone 15 (M15) and transition to new settlement arrangements at Milestone 16 (M16). 

The Programme continues to share updates through The Clock and across governance forums as we progress through 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 marked 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. 

Thank you to all 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. 

Code changes (M8) published 

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