Approved: P487 shuts down Supplier MHHS delays
Suppliers must complete migration by May 2027 or face the consequences.
Suppliers may be restricted from registering new customers if they fail to complete the migration of MPANs to the new Market-wide Half Hourly Settlement (MHHS) systems by the May 2027 deadline, thanks to Ofgem’s approval of P487.
This should not come as a surprise.
Pre-empting the need to push for delivery
Those who have witnessed other large Elexon‑led change programmes have seen them struggle with delivery discipline.
They relied heavily on goodwill, peer pressure and soft deadlines.
And eventually delivered, but often late.
MHHS is larger and more complex. Ofgem has clearly concluded that soft incentives alone are not enough. That’s why P487 is now in place: to ensure that the MHHS migration is complete by the 7th May 2027 deadline.
Higher industry costs at risk
Without the P487, the programme risks Suppliers pushing back migration, missing the deadline and then increasing overall industry costs of running legacy & MHHS systems concurrently.
Not only that, but the expected customer benefits & system savings MHHS promises will be pushed back, too.
P487 corrects this by placing the risk and consequence back on the Supplier who caused the delay.
”P487 is a clear signal from Ofgem that delivery matters as much as design. The consequence is not a fine or a penalty, but a real commercial restriction for Suppliers that fail to complete migration on time for reasons within their control.
Head of Policy & RegulationJames Murphy
Download our free resources
Access our P487 Briefings and Checklists here.
Energy Suppliers
TPIs & Consultants
Business & Public Sector
The consequence of P487 in simple terms
There is one main operational and commercial consequence for Suppliers.
If a Supplier fails to complete migration by Milestone 15 (M15) on 7 May 2027, due to reasons within the Supplier’s control, the Supplier may be temporarily restricted from registering new customers until migration is complete.
This restriction applies to new registrations only.
It does not affect existing customers and does not remove customers from a Supplier.
The intent is not to penalise delivery challenges, but to prevent avoidable delays that prolong dual running of legacy and MHHS settlement systems and increase costs for the wider market.
”“From our perspective as a data and metering service agent that is already successfully delivering services in MHHS, Ofgem’s approval of P487 creates a materially higher delivery and operational risk for energy suppliers that are dependent on agents who are not MHHS ready, or who are underperforming during migration. It changes MHHS from being primarily a programme delivery challenge into a direct commercial and regulatory threat for suppliers.”
Managing Director – Data and Digital ServicesRichard Hill
Firm deadline
All electricity supplies must migrate to MHHS by 7 May 2027
(Milestone 15 or M15 of the MHHS Programme)
Consequences
Suppliers who miss the deadline for reasons within their control
may be temporarily restricted from taking on new customers
Exemptions
System issues or some MPAN cases can count.
Delays caused by poor planning or unqualified agents do not qualify for exemptions
What does it mean for me?
Electricity Suppliers
- Missing the 7 May 2027 MHHS deadline for reasons within your control may temporarily stop you from taking on new customers
- Agent qualification, agent performance and migration timing are Supplier risks
- Early, well-planned migration reduces commercial exposure under P487
TPIs & Consultants
- Supplier readiness matters more as 7 May 2027 deadline approaches
- Some Suppliers may be unavailable for new business if they miss the deadline
- No new obligations are placed on TPIs
Businesses & Public Sector
Your electricity supply is not affected by P487
You will not be forced to change Supplier
MHHS migration is mandatory and managed by your Supplier
Summary
P487 stops Suppliers delaying MHHS by restricting new customer growth if they miss the 7 May 2027 deadline for reasons they control.
It makes it clear that MHHS migration is not to be delayed.
The question for Suppliers is not whether the incentive is strong enough, but whether they are prepared to meet it.
P487 is the industry’s warning that delay has consequences.
If this does not change behaviour, it’s likely that the next intervention almost certainly will.
Key dates
- Milestone 14 – 28th October 2026 – Suppliers, Data & Meter agents must be qualified for MHHS roles
- Milestone 15 – 7th May 2027 – All MPANs must be migrated to MHHS
Download our free resources
Access our P487 Briefings and Checklists here.
Energy Suppliers
TPIs & Consultants
Business & Public Sector
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