SEC v123.0 to implement November 2025 SEC Release and DESNZ Designation

SEC version 123.0 came into effect today, 06 November 2025, to implement the November 2025 SEC Release.

Alongside the approved modifications for this Release, SEC version 123.0 includes DESNZ designated changes relating to Virtual Wide Area Network (VWAN). The designated changes and the accompanying letter can be found here.

This Release includes six Modification Proposals, covering both DCC System impacts and legal text changes.

The following modifications were in scope of the November 2025 SEC Release:

• MP252 ‘Amending the process for Communications Hub returns’
• MP268 ‘Certificate rotation and expired Certificates’
• MP283 ‘Data Breach Reporting’
• MP286 ‘Establishment of the Privacy Sub-Committee into the SEC’
• MP290 ‘Incorporation of Category 3 Issue Resolution Proposal into the SEC – Batch 11 and GBCS Changes’
• MP297 ‘Housekeeping for November 2025 SEC Release’

The following SEC sections were affected by the November 2025 SEC Release:

• SEC Section A ‘ Definitions and Interpretation’
• SEC Section D ‘Modification Process’
• SEC Section F ‘Smart Metering System Requirements’
• SEC Section G ‘Security’
• SEC Section I ‘Data Privacy’
• SEC Schedule 4 ‘SECCo’
• SEC Schedule 8 ‘GB Companion Specifications (GBCS)’
• SEC Schedule 10 ‘Communications Hub Technical Specifications (CHTS)’
• SEC Schedule 11 ‘Technical Specification Applicability Tables (TSAT)’

• SEC Appendix I ‘CH Installation and Maintenance Support’
• SEC Appendix Q ‘IKI Certificate Policy’
• SEC Appendix AC ‘Inventory, Enrolment and Decommissioning Procedures’

• SEC Appendix AD ‘DCC User Interface Specification (DUIS)’
• SEC Appendix AF ‘Message Mapping Catalogue (MMC)’
• SEC Appendix AZ ‘VWAN Transition Document’

The following SEC Parties are impacted by the November 2025 SEC Release:

• Large Suppliers
• Small Suppliers
• Electricity Network Parties
• Gas Network Parties
• Other SEC Parties

• DCC

Where can I access the legal text for the November 2025 SEC Release?

Full marked-up versions of all impacted documents can be downloaded here.

You can download clean versions of the individual SEC documents from the SEC and Supporting Documents section of our website or via CodeWorks.

If you do not have access to CodeWorks, please use the following link: Getting access to CodeWorks

Our SEC Document Log lists the versions of each SEC document now in effect following this release.

Where can I find further information about the November 2025 SEC Release?

If you have any questions, you can call the Helpdesk at 0120 200 6600 or email SEC.Change@talan.com.