MHHS Code Freeze

The Marketwide Half Hourly Settlement (MHHS) Programme has implemented a Change Freeze which impacts the REC Change Process and its associated timescales. Visit this page to learn more about the impacts of the MHHS Change Freeze.



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MHHS Code Freeze

MHHS Code Freeze
Impacts of MHHS on the REC Change Process
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Market Half Hourly Settlement (MHHS) – Code Freeze Impact

The MHHS Programme was established to deliver the aims of the Electricity Settlement Reform Significant Code Review (SCR). When an SCR is in effect there are rules in place to prevent any Change Proposals which may impact the scope or delivery of the SCR. The MHHS programme has now implemented a Change Freeze to manage this requirement.

There are two freezes within the MHHS Programme.

Change Freeze effective from 6th December 2023. This prevents any changes to MHHS Design or Code Drafting except in the case of fixing defects or supporting the implementation of urgent change.

Core Systems Code Freeze effective from November 2024. This technical freeze prevents any changes to MHHS Central systems and impacts:

  • Central Switching Service (CSS)
  • Electricity Retail Data Service (ERDS)
  • Electricity Enquiry Service (EES)
  • And consequential changes to the Secure Data Exchange Service (SDES)

How this impacts the REC

The REC Code Manager is assessing all changes that are already in flight or are to be raised to identify any impact on the MHHS Programme.

  • If a REC Change Proposal (CP) requires change to the MHHS design or code drafting, it may have its implementation and/or progression postponed until MHHS Programme Milestone M10 has been completed (target date March – June 2025).
  • If a CP impacts MHHS Qualification or Migration, it may be delayed until MHHS Programme Migration Milestone M15 is completed (October 2026)
  • Any CP or Data Access requests requiring an amendment to an impacted technical system including changes to API or reporting may be delayed until MHHS Programme Milestone M10 has been completed (target date March – June 2025).

The REC Code Manager will keep you updated on the impacts to REC Change. If you have any questions please contact us on the Service Desk:

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R0147 Prepayment Levelisation

R0147 Prepayment Levelisation
Approved for implementation on 28 March 2024
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On 23 February 2024, the Authority issued its decision to the Code Manager, to approve R0147 - Prepayment Levelisation for implementation on 28 March 2024. The decision document can be found on the REC Portal here 

This Change Proposal will be included in the 28 March 2024 Release Plan, to reflect the approval, and the completion of the update will be confirmed via the REC Change Bulletin.  

The Authority’s decision has been published at the same time as the decision on the related Licence Modifications. The Licence Modifications and new arrangements for Payment Method Levelisation (PML) Reconciliation under the REC, will come into effect on 01 April 2024.   

The REC Code Manager is hosting R0147 Prepayment Levelisation Pre-Release Webinar on 14 March 2024 (13:00-14:30) to provide an overview of the R0147 Prepayment Levelisation before its implementation. To view the full list of topics and register your interest, click here.  

PML Reconciliation Readiness Checklist:

  • Contact and bank details confirmed  
  • Access to reporting Sharepoint  
  • Data extract on midday on 01 April 2024 – please note additional guidance has been added to the Change Proposal page on the REC Portal here. 
  • Data submission by 15 April 2024  
  • Sign up to the R0147 Prepayment Levelisation Pre-Release Webinar  

If you have any questions about this Change Proposal in advance of the webinar, please contact us at