MHHS (Market‑wide Half Hourly Settlement): Timeline, Impacts & Preparation

The biggest change to energy billing in decades, and your business will likely be affected. Find out how to prepare below.

Who needs to switch to half-hourly billing?

MHHS will apply to most non-domestic electricity users in the UK. That includes SMEs, large businesses, and organisations that don’t currently use half-hourly meters. Use the tool to find out your status in seconds.

What is the MHHS?

The Market-wide Half Hourly Settlement (MHHS) is a major reform led by Ofgem that will change how energy usage is measured and billed across the UK.

Under MHHS, all businesses will gradually switch from estimated or manual readings to automated half-hourly electricity settlements, meaning your usage will be recorded in 30-minute intervals.

This change aims to make billing more accurate, support smarter tariffs, and help the UK move closer to Net Zero.

Not sure if you’re affected by MHHS?

Enter your metre number and we’ll instantly tell you whether you need to switch to half-hourly billing.

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Key benefits of the MHHS

The Market-wide Half Hourly Settlement isn’t just a regulatory shift, it’s a chance to modernise how your business uses and pays for electricity.

Accurate, granular billing – no more estimates, better fairness
Grid flexibility & Net‑Zero alignment – supports demand shifting and renewables
Smarter tariffs – time-of-use, dynamic pricing

Learn more

Who is involved in MHHS?

Elexon helms the transformation—redeveloping BSC central systems via its Helix Programme, launching services like Load Shaping, Market‑wide Data & Volume Allocation.

Multiple working groups (Design, Architecture, Settlement Assurance) support technical design and validation.

ElectraLink continues supplying large‑meter data during and post‑migration to ensure continuity. Elex

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MHHS Timeline: What’s Happening & When

Ofgem has mapped out a detailed transition plan to ensure the entire UK market shifts to half-hourly settlement by mid-2027. Here's a breakdown of the key stages your business should be aware of:

October 2024

Suppliers must offer half-hourly electricity and gas data access to all domestic and SME customers in Profile Classes 1–4 (or consuming <732MWh/year).

February 2025

Industry tools must be ready to automatically reclassify NHH (non-half-hourly) meters to HH-ready.

March 2025

Significant data system changes begin:

Meter Time Switch Codes (MTCs) are replaced with Settlement Configuration IDs (SSCs)
Line Loss Factors (LLFs) split into new DUoS Tariff IDs
Billing systems must reflect the new settlement data structures

September 2025

Suppliers begin migrating meters to HH settlement. No hardware changes needed yet, but bills may look different.

March 2026

All remaining non-compliant meters must be physically upgraded or replaced.

May 2027

All eligible meters must be migrated and settled on a half-hourly basis.

July 2027 - Final Deadline

Profile Classes 01–04 are retired. All meters in GB must be settled using half-hourly data, no exceptions.

The Scale of the MHHA Rollout: Why It's a Big Deal

The UK energy market is about to undergo its most significant shake-up in decades. Over 30 million meters must transition to the MHHS model, yet, as of now, nearly half aren’t ready.

While smart meter adoption has improved, only 57% of meters are smart or advanced. That leaves millions of non-compliant sites that need upgrading, replacing, or reclassifying.

Installation costs and compatibility issues slow things down
Poor communication from suppliers and regulators means many businesses still aren’t aware of MHHS
Many older systems simply weren’t built for real-time energy tracking

But with final deadlines on the horizon, there’s now pressure on suppliers and brokers to educate, guide and migrate customers, before it’s too late.

Frequently Asked Questions

Why is data quality crucial?

Pre‑migration data cleansing (Feb 2023–Oct 2024) ensures accurate MPAN mapping and measurement class alignment, essential for smooth switchover

What about unmetered supplies/export MPANS's?

All existing unmetered supplies must be HH by end of 2024; export MPANs now require HH meters post‑MHHS implementation

How will personal data be managed?

P477 modification, implemented March 7 2025, secures personal data handling under GDPR within MHHS

What if issues arise during transitions?

The IRG (Issue Resolution Group) under modification P492 streamlines code changes during key milestones (M15), launched July 2025

Will changes be reversible?

No – a one‑way gate from Oct 2024 locks migrated MPANs into HH settlement to prevent backtracking

Join the ranks of thousands who have revolutionised their energy consumption.

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