Migration is the process by which Meter Point Administration Numbers (MPANs) will be migrated from the legacy arrangements to the new MHHS arrangements, and in the case of Reverse Migration, back to the Legacy arrangements from the MHHS arrangements.

The technical processes by which the migration will take place are outlined in the suite of Migration Design Artefacts. Participants should familiarise themselves with these Artefacts, as these are the processes that participants will need to follow to successfully migrate their portfolios into the new MHHS arrangements. Visit the Migration Design page of this website to view these Artefacts.

To assist participants through Migration, the Programme has also produced the Migration, Cutover and Data Strategy document and the Data Cleanse Plan, which you can view below.

To understand more about Migration, participants can attend the Migration Working Group (MWG). Please email [email protected] if you would like to join MWG.

If you have any questions about Migration, please email [email protected]

Milestone 15 (M15) Acceptance Criteria published for industry consultation 

The M15 Acceptance Criteria document defines the acceptance criteria for M15, including the Meter Point Administration Number (MPAN) states that will be ‘acceptable’ and ‘unacceptable’ at M15. 

M15 is planned to take place in October 2026, and is currently defined as ‘Full Transition Complete’, i.e., all MPANs have been migrated to the MHHS arrangements and none remain in the legacy arrangements. 

The Programme has published the M15 Acceptance Criteria document for industry consultation. The consultation period opened on Wednesday 22 November and closes at 17:00 on Wednesday 6 December 2023

You can view the document below: 

M15 Acceptance Criteria

To submit your feedback, please download the M15 Acceptance Criteria Comments Log below and save with a file name that includes the short name of your organisation. Once completed, please email the spreadsheet to [email protected]

M15 Acceptance Criteria Comments Log

The Migration Team will respond to comments and update the document in due course. The updated document will be brought to the Testing & Migration Advisory Group (TMAG) on Wednesday 20 December 2023 for approval. 

If you have any questions, please email the Migration Team at [email protected]



Migration Thresholds Document approved

During the Migration period of the Programme, a significant number of messages will be sent between industry participants which far exceeds the volumes sent during standard operations.  

To ensure that participants and Central Systems can support these increase volumes, an upper threshold that limits the total number of migrations that can be initiated across the industry on a particular day must be set. 

The Migration Thresholds Document defines that upper threshold. The document also breaks the threshold down to the Licensed Distribution System Operator (LDSO) level. This ensures that LDSOs are aware of the maximum number of migrations they will be expected to support. 

Appendix 1 summarises the modelling that was used to define the thresholds for LDSOs as set out in the document.

The document was approved by the Testing and Migration Advisory Group (TMAG) on Monday 20 November. You can find the baselined v1.0 of the Migration Thresholds Document below: 

Migration Thresholds Document

Migration Thresholds Document: Appendix 1

If you have any questions, please email [email protected]

Data Cleanse Plan Baselined and Approved

On Wednesday 19 July, the Testing and Migration Advisory Group (TMAG) approved the Data Cleanse Plan. The version 1.0 baseline document can be found below:​​​​​​​

Data Cleanse Plan

Prior to being presented and approved at TMAG, the Data Cleanse Plan was reviewed at an Assurance Meeting on Friday 7 July. This was preceded by an industry consultation period which closed on Friday 23 June.  Thank you to all Participants who reviewed and provided feedback. 

The Data Cleanse Plan details the data cleansing and population activities required to ensure the data of the required quality and completeness for use within the MHHS Migration and ongoing live operations. This includes the day-to-day activities once Meter Point Administration (MPANs) have been migrated into the new arrangements. 

To support the development of the Data Cleanse Plan, the Migration team held Technical Sessions. Papers from the Data Cleanse Plan Technical Sessions are available below for reference.

Data Cleanse Plan Technical Session 1 Papers

Data Cleanse Plan Technical Session 2 Papers

Data Cleanse Plan Technical Session 3 Papers

Data Cleanse Plan Technical Session 4 Papers

If you have any questions, please email [email protected]


blue clock

Migration, Cutover and Data Strategy Baselined and Approved

The  Migration, Cutover and Data Strategy document sets out the strategy and approach that the Programme will follow to develop a suite of policies, processes and other Artefacts to support Migration, cutover and data cleansing and population. The document also details the strategic principles that the Programme will follow to develop these detailed Artefacts, as well as the timescales under which this development will occur. 

At the extraordinary Testing & Migration Advisory Group (TMAG) meeting on 31 May 2023, the Migration, Cutover and Data Strategy was approved, subject to any open comments being addressed, where relevant.

This document has now been baselined and can be viewed below: 

Migration, Cutover and Data Strategy

If you have any questions, please email [email protected]

Migration Option Recommendation Approved

Migration Option 3, reverse migration, was discussed and approved at the Programme Steering Group (PSG) on 7 December 2022. The reverse migration option allows participants to start migrating Meter Point Administration Numbers (MPANs) to the new MHHS arrangements earlier than M14 (i.e. early adoption), with an MPAN able to move back to current arrangements once it has been switched over to the new MHHS arrangements. 

This recommendation follows the Programme’s review and analysis of the Migration Option Evaluation Framework, the Programme Participant Information Request (PPIR) responses and assessment of the anticipated impact each option would have on Programme timelines. You can view the outline of this analysis in the 7 December 2022 PSG meeting papers on the Programme Steering Group page of this website. The completed analysis was discussed at the Migration Working Group (MWG) on 8 December 2022

We incorporated this decision into the Replan Consultation, the Migration Design and development of the Migration Approach.

Thank you to all participants who provided input and information to support the assessment of these options.

If you would like to be added to either the Migration Working Group (MWG) or Migration Design Sub Group, please email [email protected]

decision group

Migration Working Group structure

The Level 3 and Level 4 Working Group structure is shown below, followed by information on the Migration Level 4 Working Group.

Migration Level 4 Working Groups

Level 4 Working Groups are open to all Subject Matter Experts (SMEs) in the specific topic area.

If you would like to attend any of the Testing & Migration Working Groups, please email [email protected]


Migration Working Group (MWG)

The MWG is responsible for developing the migration strategy and processes from an operational perspective. This is informed by the E2E MHHS Design and the process required to migrate an individual Meter Point Administration Number (MPAN) from the existing arrangements, over to the new arrangements.

The MWG will also develop the approach to test the migration processes in terms of roles/responsibilities, resourcing, governance, test management, entry/exit criteria, test tools, test scenarios and assurance.

Output from the MWG will consist of:  Migration, Cutover & Data Strategy,  Migration Testing Approach and Plan Further migration documentation as appropriate.

If you are interested in joining this Working Group as a subject matter expert, please email [email protected]


Data Cleanse Working Group (DCWG)

The DCWG is a Level 4 Working Group which sits under the Testing and Migration Advisory Group (TMAG).

The DCWG is responsible for reporting on the progress of data cleanse activities, as well as working through any issues or concerns that have been highlighted through this reporting or raised by Programme Participants while carrying out data cleanse activities.

If you are interested in joining this Working Group as a subject matter expert, please email [email protected]