What is Market-wide Half-Hourly Settlement (MHHS) and how does it work?

Market-wide Half-Hourly Settlement (MHHS) is an Ofgem-led programme that changes how electricity is billed in the UK. Instead of relying on estimated usage or daily smart meter data, suppliers will use half-hourly meter readings to charge customers for the electricity they actually use.

This will apply to both domestic and non-domestic meters. As well as accurate billing for customers, half-hourly metering will help ensure suppliers are compensated or charged for any shortfalls or excesses in their contracted electricity.

It should ensure households and businesses are billed fairly, based on real-time energy use, and will run alongside the ongoing smart meter rollout. If you don't have a smart meter, the half-hourly settlement will be based on annual consumption estimates and property type.

Here's all you need to know.

In this guide to Market-wide Half-Hourly Settlement (MHHS)...

• We explain Market-Wide Half-Hourly Settlement (MHHS) – A major UK electricity market reform that settles all usage in 30‑minute periods using half‑hourly data instead of estimates.
• How MHHS changes billing and settlement – Explains how suppliers match what they buy on the grid to what businesses actually use each half hour, improving accuracy and reducing reliance on profiles.
• Why MHHS matters for Net Zero and the grid – Shows how granular data supports time‑of‑use tariffs, flexibility, and better integration of renewables to cut carbon and peak demand.
• What MHHS means for business customers – Outlines who is affected, the role of smart/AMR meters, and what might change on bills, MPANs and tariff options.
• When MHHS is being rolled out and key milestones – Covers Ofgem’s timeline for industry testing, customer migration and the target dates by which half‑hourly settlement will apply across the market.

What is Market-wide Half-Hourly Settlement (MHHS)?

Market-wide Half-Hourly Settlement (MHHS) is an electricity market reform that requires every electricity meter in Great Britain to be settled in 30-minute periods. 

This means the electricity suppliers buy can be matched against what their customers actually use in each half hour. It is sponsored by Ofgem and delivered by Elexon, the organisation that runs the Balancing and Settlement Code (BSC).

For most small businesses, the switch happens in the background. Your supplier moves your meter onto the new arrangements, and you don’t need to sign up or change supplier. Migration is already well underway and is scheduled to finish in May 2027.

What is energy settlement?

Energy settlement is an industry reconciliation process that matches the electricity each supplier buys for its customers with how much those customers actually use. It can then charge or pay the supplier for any difference. 

Why is energy settlement important?

Energy settlement ensures accurate billing, balances the grid in real time, integrates renewable sources, and reduces waste through precise data tracking. This has often relied on estimates, especially for homes and smaller businesses without half-hourly meters, which can lead to inaccurate billing. 

MHHs means that usage is accounted for every half hour, making bills more reflective of actual consumption and helping suppliers and generators balance the grid.

How did settlement work before MHHS?

Before MHHS, most homes and small businesses were settled using “profile classes”. A profile class is a standard usage pattern that the industry used to estimate when a meter’s electricity was consumed during the day. 

This was based on the type of customer rather than their actual readings. A small office and a bakery in the same profile class could be treated as using power at the same times, even if their real patterns were very different.

Larger sites have been settled half-hourly for some time. MHHS extends this to every meter, including domestic and microbusiness supplies.

What is changing under MHHS?

By May 2027, all domestic and business electricity supply points will be settled using half-hourly data. This shift involves rolling out smart meters where possible and updating industry systems. But you don't need a smart meter to benefit from half-hourly metering, as we explain below. 

Here's a breakdown of how it will work:

• If you already have a smart meter, it will automatically provide half-hourly data.
• If you do not have a smart meter, your usage will still be settled half-hourly based on estimates considering your annual consumption and property type until you upgrade.
• Energy suppliers, brokers, and comparison tools are updating their systems to handle industry changes like new settlement codes and the phasing out of old profile classes.
• Consumers will see new information and terminology on their energy bills and contracts as part of this transition.
• The industry is also moving to a shorter settlement timetable, so suppliers’ costs are finalised months sooner than before (see the timeline below).

How many business meters are affected?

According to a Department for Energy Security and Net Zero (DESNZ) impact assessment, the non-domestic smart meter rollout covers around 3 million meters at smaller business sites, and around 67% of non-domestic installations had a smart or advanced meter as of Q1 2026. That means roughly one in three smaller business sites could still be settled on estimates rather than actual half-hourly readings.

An advanced meter is a type of business electricity meter that can store half-hourly electricity data and send it remotely to your supplier, giving you timely access to your own usage. It does the same job as a smart meter for settlement purposes.

What are the benefits of market-wide half-hourly settlement?

MHHS aims to modernise the UK energy market and provide a range of benefits for both domestic and non-domestic energy users.

Benefits for all energy users

• More accurate billing: Electricity bills will more closely reflect the energy you use, reducing reliance on estimates or outdated meter readings.
• Greater transparency: With a smart or advanced meter, you may be able to see your usage in more detail and more often, which could make energy costs easier to predict and manage.
• Increased tariff choice: Suppliers are incentivised to create innovative tariffs, including time-of-use tariffs and dynamic pricing, meaning you may be able to save money by shifting usage to off-peak times.
• Support for net zero: With more granular data, the system can use renewable energy more effectively and reduce waste, helping the UK meet its environmental targets.

A time-of-use tariff charges different unit rates for electricity depending on the time of day. Usage during cheaper off-peak periods costs less than usage at peak times. MHHS makes these tariffs easier for suppliers to offer because they are settled on what you actually use in each half hour.

Benefits for business energy users

• Cost control: Businesses, especially those with flexible or shift-based energy needs, can save by shifting consumption to cheaper periods.
• Procurement advantage: Detailed consumption data allows businesses and business energy brokers to negotiate better energy contracts and participate more actively in demand flexibility or grid balancing schemes.
• Streamlined admin: Billing and contract information will gradually become simpler, as old profile classifications are phased out.
• Fewer manual meter readings: If your smart or advanced meter is working in smart mode, your supplier receives readings automatically, so you may no longer need to submit readings yourself.

Benefits for domestic energy users

• Personalised tariffs: Time-of-use pricing and upcoming innovations will make it easier for households to control bills and take advantage of cheaper rates.
• Preparation for a smarter future: Smart meters and MHHS pave the way for home battery storage, electric vehicles, and better tools for managing your home’s energy footprint.

To switch home energy, check out our energy comparison tool.

Who is in charge of MHHS?

MHHS is an industry-wide programme with three main players:

• Ofgem, the energy regulator for Great Britain, is the programme sponsor and sets the rules and deadlines.
• Elexon runs the central settlement systems. Elexon is a not-for-profit industry body that manages the Balancing and Settlement Code. It governs how electricity is settled between generators and suppliers.
• Energy suppliers must move their customers’ meters onto the new arrangements and update their billing systems.

As a business customer, your main point of contact is your energy supplier or broker.

What is the MHHS rollout timeline?

Testing began in 2024, and the central systems went live in 2025. In late 2024, Ofgem approved a delay of around six and a half months to allow more time for testing, which pushed back the migration dates. Here are the key MHHS dates to look out for:

• October 22, 2025: Following the launch of the central systems, suppliers started migrating customers’ meters to half-hourly settlement. Migration runs for around 18 months.
• September 2025: Supply points across the UK start moving to MHHS.
• October 2026: Elexon expects to have accepted roughly 80% of meters into the new arrangements. 
• April 1, 2027: Subject to an industry decision point in October 2026, the final reconciliation period is planned to fall from 14 months to seven months.
• May 7, 2027: All suppliers must have migrated all MPANs into the new MHHS arrangements.
• July 2, 2027: The final reconciliation period is due to fall further to four months, completing the programme.

Progress so far looks steady. The MHHS Programme reported that 20.2 million meter migrations had been completed by 28 August 2026, around 60% of all meters in scope, with supplier volumes tracking the agreed migration plan.

Businesses with high electricity demand may already use half-hourly meters, but MHHS ensures all companies are included. Households with smart meters will automatically be migrated to half-hourly settlement.

During this period, you may see changes to your bills, new contract terms, and notifications from your supplier or broker.

How does MHHS impact your bills and contracts?

Although you don't need to do anything and probably won't notice much of a difference apart from more accurate bills and no need to send meter readings, there are a few things to look out for.

• Your MPAN may look different. The core 13-digit number that identifies your supply stays the same, but the supplementary codes in the top line (such as the profile class) are being replaced with new codes designed for half-hourly settlement.
• Profile class information will disappear for migrated meters.
• Expect clearer, more precise contract wording and options to access new tariffs.
• The settlement window (the time suppliers have to balance and pay for your usage) will shorten, making the system more responsive and transparent.

An MPAN (Meter Point Administration Number) is a unique reference number that identifies an electricity supply point in Great Britain. It’s printed on your electricity bill and is used by suppliers, brokers and comparison services to identify your meter and find quotes.

Here's how MPAN numbers will change under MHHS:

To find out more, check out our guide to MPAN and MPRN.

Will MHHS make your business electricity more expensive?

The effect depends on when your business uses electricity. MHHS doesn’t set prices. Your unit rates and standing charges still come from your contract. 

But suppliers’ costs will be based on actual half-hourly usage. This means businesses that use most of their power at peak times (typically late afternoon and early evening on weekdays) could see this reflected in future quotes. Businesses that can use more power off-peak may be able to find cheaper deals.

Will MHHS change my fixed-rate contract?

A fixed-rate contract usually keeps its agreed rates until the end of the term, even if your meter is migrated during that time. Any changes to tariff structure are more likely to appear when you renew or switch. Check your contract terms or ask your supplier if you’re unsure.

Why is the UK moving to MHHS?

MHHS is designed to modernise the energy system, improve billing fairness, and promote smarter, greener energy usage. Here are some of the ways the scheme plans to do that:

• It helps balance supply and demand at a national level, making better use of renewable sources and flattening expensive peak demand periods.
• Innovation will follow, with suppliers and technology providers offering new services and savings linked to how and when you use electricity.
• In its original business case for the programme, Ofgem estimated net benefits for UK consumers of between £1.6 billion and £4.5 billion by 2045 from improved efficiency, transparency and grid flexibility.

How to prepare for market-wide half-hourly settlement

The rollout is happening now and is fully automated, so you don't need to do anything to switch to half-hourly metering (though installing a smart meter may help). Even so, here are some things to consider:

• Check your meter: Make sure you have a smart meter. If not, contact your supplier about an upgrade to unlock the most benefits.
• Check that your meter is in smart mode: Some smart meters lose their connection and revert to “traditional mode”, which means they need manual readings. If you’re still being asked for readings, your supplier may need to fix this.
• Look at when you use electricity: If you can see your half-hourly data, check when your peaks happen. Moving flexible activities, such as charging vehicles or running equipment, to off-peak times could help you benefit from time-of-use tariffs.
• Review your tariff: Ask about time-of-use or flexible tariffs that could help you save money.
• Stay informed: Look out for updates from your supplier or broker about how your bills and contracts might change. Compare business energy quotes to find more cost-effective deals as the market evolves.

How does MHHS affect comparing and switching business energy?

MHHS doesn’t stop you from switching suppliers, and migration to the new arrangements shouldn’t delay a switch. In fact, more accurate usage data may make quotes more reliable, because suppliers can price your contract on how and when you actually use electricity.

MoneySuperMarket helps you compare business energy deals from a panel of UK suppliers. You can compare quotes for fixed-rate, variable and other tariff types side by side, then choose the deal that suits your business. 

Using our business energy comparison service could save you time, especially if your contract is coming up for renewal while the market adjusts to MHHS.

Market-wide half-hourly settlement (MHHS) FAQs

Still unsure about what MHHS means for your business? Check out the answers to our most frequently asked questions.

What is Market-wide Half-Hourly Settlement (MHHS)?

MHHS is a UK energy market reform that will settle all electricity using half-hourly (every 30 minutes) meter data instead of estimates, making bills more accurate.

Why is MHHS being introduced?

MHHS is being introduced to create a smarter, more flexible electricity system that supports net zero by matching what suppliers buy with what customers actually use each half hour.

Who will MHHS affect?

MHHS will eventually affect all electricity customers, including homes and businesses, once their meters are settled using half-hourly data. It applies to electricity only. Gas settlement is not part of the programme.

Do I need a smart meter for MHHS?

A smart or advanced meter that can record and send half-hourly usage data automatically is preferred, but you'll still be able to get half-hourly settlement without one.

How could MHHS change my energy bills?

MHHS should make bills more reflective of actual usage and may enable cheaper tariffs if you can shift consumption to off‑peak times.

Will MHHS happen automatically or do I need to sign up?

MHHS is a mandatory industry-wide change that will largely happen in the background, with your supplier moving you onto half-hourly settlement over time.

When will MHHS be in place?

Meter migration began in October 2025 and is due to be completed by 7 May 2027. The industry then moves to a shorter settlement timetable on 2 July 2027, which marks the end of the programme.

What are the main benefits of MHHS for businesses?

Businesses can gain more accurate cost allocation, clearer insight into usage patterns, and access to innovative time‑of‑use and flexibility tariffs that can cut costs and carbon.