P506 Balancing and Settlement Code (BSC) proposed changes
- Publication type:
- Code modification
- Publication date:
- Topic:
- Electricity supply
- Subtopic:
- Market-wide half-hourly settlement (MHHS)
Outcome of proposed changes to Balancing and Settlement Code, P506 'Unfreezing specific MDD entities to allow legacy Suppliers access to newly Qualified LDSOs’ networks during MHHS Transition'.
Details of outcome
Ofgem has decided to approve BSC Modification P506.
Start date
The implementation date for P506 is 16 January 2025.
Code modification description
As part of Market-Wide Half Hourly Settlement (MHHS), certain Market Domain Data (MDD) entities were ‘frozen’ when Modification P478 was implemented on 22 September 2025. However, the freeze has had unintended consequences for Licensed Distribution System Operators (LDSOs).
This is because, while LDSOs can create new Line Loss Factor Classes (LLFCs), they cannot create the related MDD entities that Suppliers operating in the legacy settlement arrangements require to use those LLFCs. P506 would restore LDSOs’ ability to create the relevant MDD entities, ensure that legacy suppliers can bill and settle all customers on affected networks, and ensure that those customers can contract with the supplier of their choice.
On 21 November 2025, the Chair of the BSC Panel wrote to inform us of the BSC Panel’s unanimous view that P506 should proceed as an Urgent Modification Proposal. On 25 November 2025, we granted urgency - consistent with our published guidance - on the basis that the proposal was linked to an issue that may cause a significant commercial impact on parties and consumers if not urgently addressed.
At the BSC Panel meeting on 11 December 2025, the BSC Panel unanimously considered that P506 would better facilitate Applicable BSC Objectives (c) and (d) and the BSC Panel therefore recommended its approval. We agree with the BSC Panel that the modification would better facilitate those objectives. We have, therefore, decided to approve it. In line with the BSC Panel’s recommendation, the modification shall be implemented two working days after this decision.