MHHS Milestone 14: What Energy Suppliers Need to Know 

By IMSERV Europe Ltd

MHHS Milestone 14 (M14) is under a month away. Here’s what you need to know, what energy suppliers need to have prepared, and how IMSERV can help.  

Still confused about what MHHS is all about? Check out our MHHS explained blog. 

What is M14?

Milestone 14 (M14) marks the point in the Market-wide Half-Hourly Settlement (MHHS) migration period when all suppliers, by the 28th of October 2026, must have the systems and services in place to accept Meter Point Administration Numbers (MPANs) under the new MHHS Target Operating Model (TOM). 

All suppliers must be “MHHS Qualified” and “Service Active” to comply with this milestone. For more detail on the Migration process, visit the MHHS Migration page on their website. 

What M14 Changes 

• All electricity suppliers must be MHHS Qualified and Service Active. They need the systems and services in place to accept MPANs under the new MHHS Target Operating Model (TOM). 

• Reverse migration stops. From M14, an MPAN already in the MHHS arrangements cannot move back into the legacy arrangements when a customer switches supplier. 

• Non-qualified suppliers cannot acquire new MPANs or customers. A supplier that hasn’t qualified will be prevented from registering new MPANs until they are compliant. 

• Existing customers don’t simply disappear from an unqualified supplier. The immediate consequence is a restriction on new registrations and acquisitions. 

• The market stays in migration after M14. M14 is about supplier readiness, not a switch that moves every MPAN over on the day. Many MPANs have already migrated, and others won’t move until closer to M15 on 7 May 2027, when all MPANs are due to reach their required MHHS end state. 

Why M14 Matters 

M14 is an important milestone in the shift to MHHS, which supports a smarter, more accurate, more flexible energy market, which means: 

• Settlement based on actual consumption, not estimates 

• More accurate bills and better data for suppliers and customers 

• The foundation for smart tariffs and flexibility services 

• Improved estimation accuracy  

What Suppliers Need to Know 

M14 is less than a month away. By now, most of the groundwork, reviewing metering infrastructure, cleansing data, closing readiness gaps, should already be done. If it isn’t, the priority now is engagement, not planning. 

Talk to us about where your migration activity stands. We can help you to: 

• Support you in checking your data cleanse is complete 

• Spot any remaining readiness gaps before M14 lands 
• Plan the handover of any MPANs still moving through migration  

Common Challenges 

• Legacy metering assets that don’t fit the new model 

• Data quality issues 

• Complex customer portfolios 

• Resource and operational pressures 

How IMSERV Can Help 

We’re experts at turning complex information into practical action. Our MHHS Business Readiness team and MHHS Customer Delivery team are ready to help you prepare, so the move to M14 is as smooth as possible. 

Speak to our MHHS Customer Delivery Team: Contact Us | IMSERV 

FAQs

What is M14? 

M14 is the point in the MHHS migration timetable when every electricity supplier must be MHHS Qualified and Service Active, with the systems in place to accept MPANs under the new Target Operating Model. 

What does it mean if I don’t qualify by the date? 

A supplier that hasn’t put the required arrangements in place by M14 loses the ability to take on new customers or new MPANs until it qualifies. Existing customers aren’t affected in the same way.  

Will there be another milestone? 

Yes. Milestone 15 (M15) is set for 7 May 2027, when all MPANs are due to reach their required MHHS end state. 

How can suppliers prepare for M14? 

Confirm qualification and Service Active status, finish any outstanding data cleanse, and close remaining readiness gaps. With less than a month to go, the priority now is engagement on migration activity, not starting from scratch. 

What are the long-term benefits of M14 and MHHS? 

More accurate settlement, better use of real consumption data, and the infrastructure needed for smart tariffs and flexibility services across the market.

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