Improvements to CSS Business Process Logic
Summary
This change proposal is aimed towards rectifying a collection of issues that were identified with the CSS Business Process Logic. These have been identified as follows: 1. Deactivation of an active reg. whilst in-flight switch in progress 2. Deactivation of a prior cancelled registration 3. OFAF switch containing multiple MPxN
Latest update and next planned activity
Date of latest update
Latest Update
17/06/2026 - The Code Manager has published an Update to Plan. This will be presented to the REC Technical Expert Panel at their meeting on 24 June 2026.
Impacts Overview
Impacted Consumers
Electricity
Gas
Domestic
Non-Domestic
Impacted REC Parties and Market Participants
Energy Supplier
Distribution Network Operator
Gas Transporter
DCC
Impacted REC Services
Central Switching Service (CSS)
Priority and rationale
Standard
Priority last updated on 29 May 2026
Change Reports, Impact Assessments, Consultations and Documents
Change Reports
Solution development
Problem Statement
1) Deactivation of an active reg. whilst in-flight switch in progress: There are instances where the incumbent supplier is withdrawing prior to the ‘Supply Effective from Date’, causing the accepted switch to fail at Gate Closure which occurs at 17:00hrs. This creates the scenario in which there is no longer a losing supplier for the consumer to switch from, and therefore the switch process stalls and cannot be progressed. Therefore, this has a direct impact on consumers who have a switch request which has already been accepted but CSS is not able to progress further as the switch process stops. Indeed, there have been a total of 82 missing messages observed since 1st January 2023, of which 66 messages have been related to switches where there was no registered Supplier recorded at Gate Closure. The 30th September 2023 Gate Closure was particularly impacted by this scenario and resulted in 45 registrations which did not become effective on 14th October 2023 as planned. It should also be noted that the 1st October is one of the key contracting dates for large Industrial and Commercial (I&C) consumers, consequently increasing the impact to consumers in this instance. 2) Deactivation of a prior cancelled registration: This scenario occurs when the registered supplier of a MPxN (via the active registration) is the same supplier that cancelled a previous switch for the same MPxN. In this case there is the possibility that the supplier could attempt to deactivate the active registration by accidentally providing the cancelled registration identifier. Currently, CSS still accepts the deactivation request and erroneously changes the cancelled registration state from cancelled to inactive, sending out securedInactive messages. Currently, after an MPxN is disconnected, the Supplier is required to submit a deregistration request to CSS. Therefore, there is a possibility that the suppliers could submit this request for a cancelled registration not active registration. CSS would still accept this request as the Business Data Validation Rules (BDVR) lack coverage of this case; in such cases the Supplier may incorrectly believe that they have deregistered the MPANs. 3) OFAF switch containing multiple MPxN: This is the instance where the end user sends through a One Fail All Fail (OFAF) switch with the same MPxN contained within the payload 2 or more times. Multiple registration IDs are created for the same MPxN, and the registration is left in an incorrect state given a lack of appropriate BDVRs. Indeed, there has been a further reported incident regarding an OFAF transaction of the same MPxN. The primary MPxN was associated with a secondary MPxN and therefore two registrations were created for the primary and secondary MPxN, equating to four registrations in total. There was then an objection raised but this only cancelled 1 of the 2 registrations for each MPxN. The remaining 2 registrations proceeded through gate closure.
Proposed solution summary
- Deactivation of an active reg. whilst in-flight switch in progress As mentioned previously, the ‘Deactivation of an active reg. whilst in-flight switch in progress’ issue did have an existing REC CP raised and therefore is further along the discussion process compared to the other two issues identified. Initial discussion outlined that the most appropriate solution for this change proposal should consider the business needs and the desired outcomes. It was noted that from a business perspective, if the switch has already been accepted, then it should still go through and not be cancelled. Therefore, the following points were raised: • It was acknowledged that there are multiple solution options/approaches that could potentially be employed to resolve this issue. As such, and to avoid being overly prescriptive, it is requested that CSS provider investigate all possible options and outline their recommendation for the most suitable approach, which would be developed/progressed further through the subsequent Impact Assessments. • However, the aim is for an effective solution to be developed which would ensure that the consumer is switched with the original effective date being used and that CSS systems could cater for such registration events whilst following the normal Gate Closure processes. • Where possible, the solution should also look to proactively mitigate the impact of this scenario, as opposed to working on a retrospective basis which can lead to the issue persisting over an extended period of time. It was also noted that consideration would need to be given to state of the meters as this would also have an impact on whether switches are able to progress: Therefore, the following points were raised: • The solution would need to consider how the incumbent supplier has deactivated the meter and whether it has been moved to a ‘terminated’ state or a ‘dormant’ state. o Dormant – The meter is inactive. Note that this is a temporary state and therefore the meter could be put back into service. o Terminated – The meter has reached end of life and cannot be reinstated. Note that this is a permanent state. • If the incumbent supplier has moved the meter into a ‘terminated’ state, the in-flight switch would then need to be cancelled. • However, for the ‘dormant’ state, the following two options would be available in terms of what could happen to the status of the meter and thus the in-flight switch: o Moves from ‘inactive’ to ‘active’ (continue with the switch) o Moves from ‘inactive’ to ‘cancelled’ (cannot continue with the switch)
- Deactivation of a prior cancelled registration and OFAF switch contains multiple of the same MPxN It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses.
No documents available.
There is currently no Change Plan.
Original submission
Change details
Caroline Milner - REC Technical Services
3 Jun 2024
Change details
Improvements to CSS Business Process Logic
This change proposal is aimed towards rectifying a collection of issues that were identified with the CSS Business Process Logic.
These have been identified as follows:
1. Deactivation of an active reg. whilst in-flight switch in progress
2. Deactivation of a prior cancelled registration
3. OFAF switch containing multiple MPxN
These have been identified as follows:
1. Deactivation of an active reg. whilst in-flight switch in progress
2. Deactivation of a prior cancelled registration
3. OFAF switch containing multiple MPxN
1. Deactivation of an active reg. whilst in-flight switch in progress:
There are instances where the incumbent supplier is withdrawing prior to the ‘Supply Effective from Date’, causing the accepted switch to fail at Gate Closure which occurs at 17:00hrs.
Indeed, there have been a total of 82 missing messages observed since 1st January 2023, of which 66 messages have been related to switches where there was no registered Supplier recorded at Gate Closure.
The 30th September 2023 Gate Closure was particularly impacted by this scenario and resulted in 45 registrations which did not become effective on 14th October 2023 as planned.
It should also be noted that the 1st October is one of the key contracting dates for large Industrial and Commercial (I&C) consumers
This creates the scenario in which there is no longer a losing supplier for the consumer to switch from, and therefore the switch process stalls and cannot be progressed. Therefore, this has a direct impact on consumers who have a switch request which has already been accepted but CSS is not able to progress further as the switch process stops
2. Deactivation of a prior cancelled registration
This scenario occurs when the registered supplier of a MPxN (via the active registration) is the same supplier that cancelled a previous switch for the same MPxN. In this case there is the possibility that the supplier could attempt to deactivate the active registration by accidentally providing the cancelled registration identifier.
Currently, CSS still accepts the deactivation request and erroneously changes the cancelled registration state from cancelled to inactive, sending out SecuredInactive messages.
Currently, after an MPxN is disconnected, the Supplier is required to submit a deregistration request to CSS. Therefore, there is a possibility that the suppliers could submit this request for a cancelled registration not active registration. CSS would still accept this request and in those cases the Supplier may incorrectly believe that they have deregistered the MPANs.
3. OFAF switch containing multiple MPxN
This is the instance where the end user sends through a One Fail All Fail (OFAF) switch with the same MPxN contained within the payload 2 or more times. Multiple registration IDs are created for the same MPxN, and the registration is left in an incorrect state even though Business Data Validation Rules (BDVR).
Incidents being reported include an OFAF transaction of the same MPxN. The primary MPxN was associated with a secondary MPxN and therefore two registrations were created for the primary and secondary MPxN, equating to four registrations in total. There was then an objection raised but this only cancelled 1 of the 2 registrations for each MPxN. The remaining 2 registrations proceeded through gate closure.
There are instances where the incumbent supplier is withdrawing prior to the ‘Supply Effective from Date’, causing the accepted switch to fail at Gate Closure which occurs at 17:00hrs.
Indeed, there have been a total of 82 missing messages observed since 1st January 2023, of which 66 messages have been related to switches where there was no registered Supplier recorded at Gate Closure.
The 30th September 2023 Gate Closure was particularly impacted by this scenario and resulted in 45 registrations which did not become effective on 14th October 2023 as planned.
It should also be noted that the 1st October is one of the key contracting dates for large Industrial and Commercial (I&C) consumers
This creates the scenario in which there is no longer a losing supplier for the consumer to switch from, and therefore the switch process stalls and cannot be progressed. Therefore, this has a direct impact on consumers who have a switch request which has already been accepted but CSS is not able to progress further as the switch process stops
2. Deactivation of a prior cancelled registration
This scenario occurs when the registered supplier of a MPxN (via the active registration) is the same supplier that cancelled a previous switch for the same MPxN. In this case there is the possibility that the supplier could attempt to deactivate the active registration by accidentally providing the cancelled registration identifier.
Currently, CSS still accepts the deactivation request and erroneously changes the cancelled registration state from cancelled to inactive, sending out SecuredInactive messages.
Currently, after an MPxN is disconnected, the Supplier is required to submit a deregistration request to CSS. Therefore, there is a possibility that the suppliers could submit this request for a cancelled registration not active registration. CSS would still accept this request and in those cases the Supplier may incorrectly believe that they have deregistered the MPANs.
3. OFAF switch containing multiple MPxN
This is the instance where the end user sends through a One Fail All Fail (OFAF) switch with the same MPxN contained within the payload 2 or more times. Multiple registration IDs are created for the same MPxN, and the registration is left in an incorrect state even though Business Data Validation Rules (BDVR).
Incidents being reported include an OFAF transaction of the same MPxN. The primary MPxN was associated with a secondary MPxN and therefore two registrations were created for the primary and secondary MPxN, equating to four registrations in total. There was then an objection raised but this only cancelled 1 of the 2 registrations for each MPxN. The remaining 2 registrations proceeded through gate closure.
1. Deactivation of an active reg. whilst in-flight switch in progress
As mentioned previously, the ‘Deactivation of an active reg. whilst in-flight switch in progress’ issue did have an existing REC CP raised and therefore is further along the discussion process compared to the other two issues identified.
Initial discussion outlined that the most appropriate solution for this change proposal should consider the business needs and the desired outcomes. It was noted that from a business perspective, if the switch has already been accepted, then it should still go through and not be cancelled. Therefore, the following points were raised:
It was acknowledged that there are multiple solution options/approaches that could potentially be employed to resolve this issue. As such, and to avoid being overly prescriptive, it is requested that CSS provider investigate all possible options and outline their recommendation for the most suitable approach, which would be developed/progressed further through the subsequent Impact Assessments.
However, as some overarching principles, the aim is for an effective solution to be developed which would ensure that the consumer is switched with the original effective date being used and that CSS systems could cater for such registration events whilst following the normal Gate Closure processes.
Where possible, the solution should also look to proactively mitigate the impact of this scenario, as opposed to working on a retrospective basis which can lead to the issue persisting over an extended period of time.
It was also noted that consideration would need to be given to state of the meters as this would also have an impact on whether switches are able to progress: Therefore, the following points were raised:
• Solution would need to consider how the incumbent supplier has deactivated the meter and whether it has been moved to a ‘terminated’ state or a ‘dormant’ state.
• Dormant - Inactive but this is a temporary status and therefore could be put back into service (i.e., it is a temporary state).
• Terminated - Meter has reached end of life and cannot be reinstated (i.e., it is a permanent state)
• If the incumbent supplier has moved the meter into a ‘terminated’ state, the in-flight switch would then need to be cancelled
• However, for the ‘dormant state’, the following two options would be available in terms of what could happen to the status of the meter and thus the inflight switch:
• Moves from ‘inactive to active’ (continue with the switch)
• Moves from ‘inactive to cancelled’ (cannot continue with the switch)
Deactivation of a prior cancelled registration and OFAF switch contains multiple of the same MPxN
It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses
2. Deactivation of a prior cancelled registration and 3. OFAF switch contains multiple of the same MPxN
It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses
As mentioned previously, the ‘Deactivation of an active reg. whilst in-flight switch in progress’ issue did have an existing REC CP raised and therefore is further along the discussion process compared to the other two issues identified.
Initial discussion outlined that the most appropriate solution for this change proposal should consider the business needs and the desired outcomes. It was noted that from a business perspective, if the switch has already been accepted, then it should still go through and not be cancelled. Therefore, the following points were raised:
It was acknowledged that there are multiple solution options/approaches that could potentially be employed to resolve this issue. As such, and to avoid being overly prescriptive, it is requested that CSS provider investigate all possible options and outline their recommendation for the most suitable approach, which would be developed/progressed further through the subsequent Impact Assessments.
However, as some overarching principles, the aim is for an effective solution to be developed which would ensure that the consumer is switched with the original effective date being used and that CSS systems could cater for such registration events whilst following the normal Gate Closure processes.
Where possible, the solution should also look to proactively mitigate the impact of this scenario, as opposed to working on a retrospective basis which can lead to the issue persisting over an extended period of time.
It was also noted that consideration would need to be given to state of the meters as this would also have an impact on whether switches are able to progress: Therefore, the following points were raised:
• Solution would need to consider how the incumbent supplier has deactivated the meter and whether it has been moved to a ‘terminated’ state or a ‘dormant’ state.
• Dormant - Inactive but this is a temporary status and therefore could be put back into service (i.e., it is a temporary state).
• Terminated - Meter has reached end of life and cannot be reinstated (i.e., it is a permanent state)
• If the incumbent supplier has moved the meter into a ‘terminated’ state, the in-flight switch would then need to be cancelled
• However, for the ‘dormant state’, the following two options would be available in terms of what could happen to the status of the meter and thus the inflight switch:
• Moves from ‘inactive to active’ (continue with the switch)
• Moves from ‘inactive to cancelled’ (cannot continue with the switch)
Deactivation of a prior cancelled registration and OFAF switch contains multiple of the same MPxN
It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses
2. Deactivation of a prior cancelled registration and 3. OFAF switch contains multiple of the same MPxN
It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses
It is noted that a REC CP (R0153) was raised titled ‘Catering for registration events where the incumbent Supplier deactivates prior to a switch becoming effective’. This related to the issue highlighted by the first bullet point above. Following a review of that change, we intend to withdraw R0153 and raise a new change which would encompass all the identified issues into one.
Impacts
Electricity, Gas, Domestic Prepayment, Domestic Credit, Microbusiness, Small and Medium Enterprise (SME), Industrial and Commercial (I&C)
Switching experience, Trust and confidence
-
No details provided
-
No details provided
-
No details provided
-
No details provided
CSS Message Business Data Validation Rules
No details provided
-
Central Switching Service (CSS)
-
Energy Suppliers, Distribution Network Operators, Gas Transporters, DCC
-
No details provided
-
No
No details provided
Priority & timing
No
-
No
No
No details provided
-
Activity
Proposed solution summary changed to Deactivation of an active reg. whilst in-flight switch in progress As mentioned previously, the ‘Deactivation of an active reg. whilst in-flight switch in progress’ issue did have an existing REC CP raised and th…
Proposed solution summary changed to Deactivation of an active reg. whilst in-flight switch in progress As mentioned previously, the ‘Deactivation of an active reg. whilst in-flight switch in progress’ issue did have an existing REC CP raised and therefore is further along the discussion process compared to the other two issues identified. Initial discussion outlined that the most appropriate solution for this change proposal should consider the business needs and the desired outcomes. It was noted that from a business perspective, if the switch has already been accepted, then it should still go through and not be cancelled. Therefore, the following points were raised: • It was acknowledged that there are multiple solution options/approaches that could potentially be employed to resolve this issue. As such, and to avoid being overly prescriptive, it is requested that CSS provider investigate all possible options and outline their recommendation for the most suitable approach, which would be developed/progressed further through the subsequent Impact Assessments. • However, the aim is for an effective solution to be developed which would ensure that the consumer is switched with the original effective date being used and that CSS systems could cater for such registration events whilst following the normal Gate Closure processes. • Where possible, the solution should also look to proactively mitigate the impact of this scenario, as opposed to working on a retrospective basis which can lead to the issue persisting over an extended period of time. It was also noted that consideration would need to be given to state of the meters as this would also have an impact on whether switches are able to progress: Therefore, the following points were raised: • The solution would need to consider how the incumbent supplier has deactivated the meter and whether it has been moved to a ‘terminated’ state or a ‘dormant’ state. o Dormant – The meter is inactive. Note that this is a temporary state and therefore the meter could be put back into service. o Terminated – The meter has reached end of life and cannot be reinstated. Note that this is a permanent state. • If the incumbent supplier has moved the meter into a ‘terminated’ state, the in-flight switch would then need to be cancelled. • However, for the ‘dormant’ state, the following two options would be available in terms of what could happen to the status of the meter and thus the in-flight switch: o Moves from ‘inactive’ to ‘active’ (continue with the switch) o Moves from ‘inactive’ to ‘cancelled’ (cannot continue with the switch)Deactivation of a prior cancelled registration and OFAF switch contains multiple of the same MPxN It is noted that the initial approach discussed was to add new Business Data Validation Rules (BDVR) to stop these issues from occurring. However, this was only discussed at high-level and therefore we request that the CSS provider confirm this approach and provide further details as this change proposal progresses..
Show moreImplementation Date has been updated to 25 Jun 2027.
Change Report - Initial Assessment and Change Plan Report has been updated to Comments deadline for R0178 - Update to Plan (17.06.2026) Pre-Approval.pdf - 2026-06-24.
holly.law has been allocated as Lead Analyst.
Status has been changed to Solution Development.
james.hardy has been allocated as Lead Analyst.
maxime.van-eyseren has been allocated as SME.