As the market operator, MOSL manages changes to the Market Arrangements Code (MAC) and Wholesale Retail Code (WRC) on behalf of the non-household market. Anybody can propose a change to the codes provided it passes the Initial Acceptance Criteria, which are applied by the market operator, and the Acceptance & Prioritisation Criteria, which are applied by the Code Change Committee. MOSL supports proposers to develop proposals for acceptance and if accepted to develop solutions for recommendation to Ofwat for approval. MOSL may also propose its own changes and solutions.

This page provides information on past and current changes. Please use the links to the right for consultations on current changes, guidance on the change process and how to propose a change. MOSL also provides the Code Change Committee with a monthly report describing the progress of each change proposal and anticipated releases of changes to the codes and central systems. The latest report can be downloaded from the link on the right.  Previous reports can be found in Code Change Committee papers.

Change Proposals

The Change Register below shows all proposals that have been formally submitted which have been accepted or will be assessed by the Code Change Committee for acceptance into the change process. Changes to the Market Arrangements Code are prefixed CPM and changes to the Wholesale Retail Code are prefixed CPW. Some changes impact both codes.

Following the implementation of CPM053 on 18 December 2023, formally submitted changes that fail the Initial Acceptance Criteria applied by the Market Operator will not be assessed by the Code Change Committee. These pipeline changes are prefixed by PIP and will be published on this website in due course. 

By default, the table below sorts changes by where they are in the process with those in the early stages at the top and those implemented, rejected or withdrawn at the end. Clicking the table headings sorts by reference, title, status or implementation date. The filters can be used to search for a specific change, status or implementation date.  If a change has multiple parts with different statuses then its status will be 'See Change Summary'.  A summary of each change and documentation associated with it can be viewed by clicking on the change title link within the table.

Change Register

Reference Title Status Implementation date
CPW151 WRC Housekeeping Pending CCC Acceptance -
CPW139 & CPM051 Bilateral Hub See change summary -
CPM058 & CPW149 Market Performance Framework Reform See change summary 01/04/2025
CPM052 & CPW140 BR-MeX (business customer and retailer measure of experience) Design 01/04/2025
CPW150 Governance of Incentive Scheme Guidance Documents Design 25/10/2024
CPM059 MAC & MOSL Articles Duplication Design 06/12/2024
CPW132 Credit Support and Wholesaler Credit Ratings Ofwat Decision 18/01/2024
CPW142 Wholesaler Smart Meter Reads Ofwat Decision 06/12/2024
CPM054 & CPW145 Deductions and withholdings under formal Disputes Process Ofwat Decision 29/11/-0001
CPW148 Transfer Read Notifications for Outgoing Retailers Implementing 06/12/2024
CPW001 Cross Border Matters Implemented 02/10/2017
CPW002 CSD0301 Updates - Meter Treatment Implemented 02/10/2017
CPW003 CSD0301 Updates - Meter Networks Implemented 02/10/2017
CPW004 CSD0301 Updates - Meter Networks (Future) Implemented 02/10/2017
CPW005 Self Supply Implemented 03/07/2017
CPW006 CSD0301 - New data item updates Implemented 02/10/2017
CPW007 Alignment to Customer Protection Code of Practice Implemented 02/10/2017
CPW008 Direction to Supply Implemented 02/10/2017
CPW009 CSD 0302 updates - alignment with CSD 0301 Implemented 02/10/2017
CPW010 Emergency Contact Details Implemented 28/09/2018
CPW014 CSD 0301 Updates Implemented 18/05/2018
CPW015 CSD 0101 Clarification Implemented 02/10/2017
CPW016 CSD0104 Clarification – Meter Networks Implemented 02/10/2017
CPW017 CSD0105 Clarifications and updates Implemented 02/10/2017
CPW018 Clarification of Unsecured Credit Allowance Implemented 23/04/2018
CPW019 Alternative Eligible Credit Support Implemented 31/07/2018
CPW020 Proposal to amend the wording in the F02 Complaint Form Implemented 01/12/2017
CPW021 Negotiating Alternative Eligible Credit Support reasonably and in good faith Implemented 14/07/2017
CPW022 New Connection Retailer Unknown Implemented 18/05/2018
CPW023 Market Entry and Re-Assurance Updates Implemented 12/03/2018
CPW024 Settlement Renaming and Report Issuing Updates Implemented 01/12/2017
CPW025 Extending TCORR Functionality for Inactive Data Items Implemented 17/05/2019
CPW026 Removing SPID version design Implemented 28/09/2018
CPW027 QC Error Code Implemented 18/05/2018
CPW028 Unpaired SPIDs Implemented 28/09/2018
CPW029 & CPM007 GDPR and Data Protection Provisions Updates Implemented 30/03/2018
CPW030 Review of Market Performance Standards Implemented 01/04/2018
CPW031 Extending the new connection suspension period Implemented 03/03/2018
CPW032 Amend H/04 to clarify Tariff effective date Implemented 28/09/2018
CPW033 Meter effective to date field in MDS_METER report Implemented 26/10/2018
CPW034 Housekeeping changes to CSD 0301 Implemented 25/05/2018
CPW035 F01 Form Amendments Implemented 28/09/2018
CPW036 G/02 Form Amendments and G/03 Temporary Consent Form Implemented 28/09/2018
CPW037 Removing the Error Codes list from CSD 0301 Implemented 28/09/2018
CPW038 Tariffs Report updates Implemented 17/05/2019
CPW039 & DCP002 Deferral of Final Settlement Runs Implemented 31/08/2018
CPW040 Changes to the contents of the NAPS Report Implemented 17/05/2019
CPW041 G read removal governance Implemented 29/03/2019
CPW042 Provision of adding re–read flag into the MDS Meter Reads file Implemented 17/05/2019
CPW043 Drafting clarifications for CPW028 Implemented 26/10/2018
CPW044 Digital Certificates & Public Keys updates Implemented 03/12/2018
CPW045 Updates to the Service Management Interface Implemented 03/12/2018
CPW046 Changes to the unplanned settlement process Implemented 03/12/2018
CPW064 Changes to Corrective Settlement Runs for Individual Supply Points Implemented 14/02/2020
CPW065 Retailer Notifications Implemented 15/05/2020
CPW066 Estimation Review Implemented 14/02/2020
CPW068 & CPM017 Market Incident Management Plan Committee Revisions Implemented 28/08/2020
CPW070 & CPM043 Bilateral Transactions Implemented 29/11/2022
CPW072 Setting MPS 15 charges to zero Implemented 01/11/2019
CPW073 Updates to GDPR Personal Data Warnings in CSD 0301 Implemented 14/02/2020
CPW074 Introduction of a Retailer SLA in relation submission of trade effluent market forms to Wholesalers. Implemented 28/08/2020
CPW077 Establishing Trade Effluent charging strength methodology Implemented 06/11/2020
CPW078/CPM020 Priority Performance Regime Changes for April 2020 Implemented 01/04/2020
CPW079 Protections for Credit Support Security Implemented 14/02/2020
CPW081 Improving transparency of Alternative Payment Terms Implemented 01/04/2020
CPW082 Gap Site Incentive Scheme Implemented 01/04/2020
CPW083 Vacancy Incentive Scheme Implemented 15/05/2020
CPW084 Introducing a Retailer Measure of Experience (R-MeX). Implemented 01/04/2020
CPW085 Premises Vacant transaction link to DPID Implemented 29/11/2022
CPW087 Ability for Wholesalers to add meter reads Implemented 06/11/2020
CPW089 T101 Adding Billing Address fields Implemented 14/05/2021
CPW091 Temporary Changes to Vacancy Implemented 30/03/2020
CPW092/CPM029 Unified Disputes Process and Committee Implemented 13/11/2020
CPW093 Payment deferral interim measures Implemented 30/03/2020
CPW094 Temporary Change to Disconnections Implemented 08/04/2020
CPW095 Urgent: Maintain Credit Requirements Implemented 16/04/2020
CPW096 Urgent: Payment Deferral Medium Term Implemented 01/05/2020
CPW099 Clarify the responsibilities of Trading Parties during a planned event Implemented 14/05/2021
CPW101/CPM031 Unwinding Temporary Covid-19 Arrangements in the Business Retail Market Implemented 01/08/2020
CPW102/CPM030 Gender Neutrality in the Market Codes Implemented 06/11/2020
CPW103/CPM032 Interim Supply Process Amendments Implemented 09/09/2020
CPW104 Housekeeping changes to facilitate the Performance Regime introduced in April 2020 Implemented 15/02/2021
CPW105 Provisions of Information Obligation Implemented 26/08/2022
CPW107 Covid-19 Temporary Vacancy exemptions for Credit Support Implemented 23/10/2020
CPW108 Agreement to Unplanned Settlement Runs Implemented 26/01/2021
CPW109 Changing the Constraints on Customer Reads Implemented 09/07/2021
CPW111 Housekeeping change to align the codes with CMOS Implemented 14/05/2021
CPW112 Clarifications to CSD 0102 and CSD 0105 Implemented 14/05/2021
CPW113 Housekeeping Changes to Correct Typographical Errors and Enhance Standardisation Implemented 14/05/2021
CPW114/CPM037 Housekeeping Changes to Correct Typographical Errors and Enhance Standardisation Implemented 14/05/2021
CPW116 & CPM038 Clarification and removal of redundant clauses in the Unified Disputes Process Implemented 01/09/2021
CPW117 Shortening the late payment default timeline for a credit support reduction Implemented 05/11/2021
ICP/WRC003 Alignment with Exit Regulations Implemented 02/10/2017
ICP/WRC036 Data Format Updates Implemented 02/10/2017
ICP/WRC048 Tariff Table Updates Implemented 02/10/2017
ICP/WRC051 Performance Charge Alignment with ISA Implemented 02/10/2017
ICP/WRC053 SPID Pairing Updates Implemented 02/10/2017
ICP/WRC055 Trade Effluent Updates - SVAM Subtract and Calculated Discharge Frequency Implemented 02/10/2017
ICP/WRC059 Settlement Updates Implemented 02/10/2017
CPM001 Change Proposal Form Update Implemented 03/07/2017
CPM003 Revised MIMP Committee Composition Implemented 01/12/2017
CPM004 Board Nomination Process Extension Implemented 15/09/2017
CPM006 Introducing a process for Urgent Change Proposals Implemented 08/04/2020
CPM008 Redistribution of Market Performance Standards Charges Implemented 29/03/2019
CPM009 Further Board Nomination Process Extension Implemented 16/03/2018
CPM010 Amendments to the Retailer Board Nomination Process Implemented 31/07/2018
CPM011 MOSL invoices and payment terms Implemented 31/07/2018
CPM013 Adding the Customer Representative as a Voting Panel Member Implemented 20/09/2019
CPM014 Market Performance Standards Charges Redistribution Payment Clarification Implemented 26/07/2019
CPM016 Panel Voting Majorities Implemented 23/08/2019
CPM018 Treatment of Market Performance Standard charges and Operational Performance Standard charges Implemented 01/01/2020
CPM019 GDPR Data Security Standards Implemented 06/11/2020
CPM022 Urgent Change: Reducing Panel Quorum Implemented 07/10/2020
CPM023/CPW090 Suspension of Performance Standard Charges Implemented 23/03/2020
CPM024 Urgent housekeeping alignment of CPM020 with CPM023 Implemented 01/04/2020
CPM025/CPW097 Suspension of Market Performance Standard Charges following an interim supply event Implemented 01/07/2020
CPM026 Panel Chair and Alternate Implemented 28/08/2020
CPM027/CPW098 Extending the Suspension of Market and Operational Performance Standard Charges due to Covid 19 Implemented 01/06/2020
CPM028 Aligning MOSL Board Governance with the Articles of Association Implemented 01/09/2020
CPM033 Improved process for managing Data Subject Rights Requests Implemented 14/05/2021
CPM034 Retailer Panel Member Changes Implemented 01/02/2021
CPM036 Provision to vary term of Panel Members Implemented 28/01/2021
CPW047 Enabling Sewerage Wholesalers to create meter networks Implemented 26/07/2019
CPW048 Alternative Payment Terms Implemented 31/01/2019
CPW049 & CPM012 Operational Performance Standards Review Implemented 01/04/2019
CPW050 Changes to the Long Unread Meters Report Implemented 26/07/2019
CPW051 Market Incident Management Plan amendments Implemented 29/03/2019
CPW052 Improving transparency of Alternative Credit Arrangements Implemented 29/03/2019
CPW053 MO Transaction Processing and Reporting Implemented 17/05/2019
CPW054 Housekeeping Changes to Market Codes Implemented 29/03/2019
CPW055 Wholesale Retail Code inconsistency Implemented 28/02/2019
CPW056 Cascade Erasure Implemented 08/11/2019
CPW057 Improving transparency of Credit Guarantee Arrangements Implemented 30/09/2019
CPW058 Removing Processes A1-A5 (Developer Services) Implemented 26/07/2019
CPW059 Changes to Review Obligations Implemented 15/02/2021
CPW060 Clarifying credit scores and ratings for the purposes of Unsecured Credit Allowances Implemented 30/09/2019
CPW119 & CPM042 Dormant Trading Party Provisions Implemented 05/11/2021
CPW120 Final Meter Reads where no Visual Read is available Implemented 12/05/2023
CPM039 & CPW124 Revisions to Panel Composition Implemented 01/09/2021
CPM040 & CPW121 MAC and WRC Principles Implemented 01/09/2021
CPW123 Improved codes for ‘remote read type' Implemented 13/05/2022
CPM044 Management of the Ofwat Innovation Fund Implemented 17/11/2021
CPW126 Settling of Post RF Primary Charges Implemented 26/08/2022
CPM045 & CPW127 Extending the right of the Market Operator to raise Change Proposals Implemented 14/01/2022
CPW128 Updating Volume Validations Tolerance Implemented 12/05/2023
CPM047 Change to Panel Quorum Implemented 14/01/2022
CPW130 Transfer Read Estimated Reason Codes Implemented 12/05/2023
CPW134 Clarifications to default provisions Implemented 02/08/2022
CPW135 CPW135 WRC Housekeeping Implemented 29/11/2022
CPM049 MAC Housekeeping Implemented 03/03/2023
CPM050 Data Cleanse Funding Implemented 22/05/2023
CPW136 Drawing credit following Retailer exit Implemented 07/04/2023
CPW137 Interim Supply: Customer Data Provisions Implemented 27/10/2023
CPW138 Housekeeping changes post CPW070 & CPM043 Implemented 20/06/2023
CPW141 Clarification of read definitions and meter chamber ownership Implemented 16/02/2024
CPW143 Wholesaler Maintenance of YVEs for Non Market Meters Implemented 10/05/2024
CPW144 Market Performance Framework Incremental Improvements Implemented 18/12/2023
CPM053 & CPW146 Change Process Improvements Implemented 18/12/2023
CPM055 CMOS Data Escrow Implemented 16/02/2024
CPW147 MPS18 & 19 clarification Implemented 18/01/2024
CPM056 Resource support to industry groups Implemented 04/04/2024
CPM057 Late Payment of MO Charges Implemented 04/04/2024
CPW012 Flags on D1 Disaggregated Settlement Report Rejected -
CPW013 Meter Reading Validation Rejected -
CPW069 Right of a Retailer to appoint an Accredited Entity to repair or replace a faulty meter when a Wholesaler misses the associated SLA Rejected -
CPW075 Settlement Estimation - Remove estimated meter readings when forward estimating Rejected -
CPW080 Simplification of the Default and Termination Process Rejected -
CPW086 Unsecured Credit Allowance – Rebalancing Rejected -
CPW088 Ability for Wholesalers and Retailers to add Meter Location Data, and GIS X/Y Details. Rejected -
CPW100 Urgent: Revision to Credit Support Requirement under CPW095 Rejected -
CPW110 & CPM041 Sharing Non-Household Emergency Contact Details Rejected -
CPW115 Amending and updating the definition of Insolvency Event to remove the ‘negative net assets’ criterion Rejected -
CPM015 & CPW071 Panel self-governance Rejected -
CPM021 & CPW125 Panel Membership and Voting Rights Rejected -
CPM035 Panel Election Streamlining Rejected -
CPW061 Unsecured Credit Allowance reflecting payment history Rejected -
CPW062 Household Indicator Flag Rejected -
CPW118 Minimum Meter Read Frequency Rejected 13/05/2022
CPW122 Introducing Direct Debit as a Payment Method Rejected -
CPM046 and CPW133 Approved Codes of Practice Rejected -
CPW129 Review of Post RF Materiality Threshold Rejected -
CPM048 & CPW131 Suspending certain MPS charges pending full review of the MPF Rejected -
CPW011 New Read Type D3010 Withdrawn -
CPW063 Chargeable Data - Fixed RTS Withdrawn -
CPW067 Bulk Submission of Service Requests via MS Excel Withdrawn -
CPW076 Change to the current KPI for CSD002 OPS Measure C1a Withdrawn -
CPW106 Management of Long-Term Vacant Supply Points Withdrawn -
CPM005 Market Entry and Re-Assurance Updates Withdrawn -

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