What Is Market-Wide Half-Hourly Settlement (MHHS) and What Does It Mean for Your Business?

Market-Wide Half-Hourly Settlement (MHHS) is changing how electricity consumption is accounted for across Great Britain. Almost every electricity metering point, around 33 million in total, is moving to half-hourly settlement, with migration running from October 2025 to May 2027.

Elexon, which runs the electricity settlement process, describes MHHS as one of the biggest changes to the electricity retail market since competition began in the late 1990s. The MHHS Programme reported in July 2026 that half of all industry metering points had already migrated. Yet most businesses have heard little about it because, for the majority, there is nothing they need to do.

That does not make MHHS irrelevant. By giving the market a more detailed picture of when electricity is used, it creates more scope for suppliers to offer tariffs and products that reflect actual usage patterns. Understanding what MHHS changes, and what it does not, can help your business make better decisions when it next reviews its energy contract.

What Settlement Actually Is

Settlement is the part of the electricity market almost nobody sees, and it sits behind every bill.

Electricity is traded in half-hourly periods, and suppliers contract for volumes in advance based on what they expect customers to use. Settlement is the industry process, run by Elexon under the Balancing and Settlement Code, that works out how much each supplier’s customers actually used in every half hour and compares it with those contracted volumes. Where the two do not match, the difference is settled through the imbalance process.

For that to work, the industry needs to know when electricity was used, not just how much in total. Larger sites on half-hourly meters have recorded consumption that way for years. Smaller businesses on non-half-hourly meters have not, so the industry filled the gap with load profiles: standard patterns of usage applied to millions of sites. As Elexon put it earlier this year, the industry was “previously using about 2,000 meters to get what the shape is”.

It is the equivalent of a restaurant splitting the bill evenly across the table: broadly fair on average, and wrong for almost everyone individually. If your business runs mostly overnight, or shuts at lunchtime, the profile applied to your meter did not reflect that.

What MHHS Changes

Once a metering point has migrated, it is settled on a half-hourly basis. How that half-hourly picture is produced depends on the meter.

Where a meter can provide actual half-hourly consumption data, typically a smart or advanced meter, that data is used for settlement instead of an estimated pattern.

Where it cannot, consumption is still settled half-hourly, but an estimated shape is produced by Elexon’s Load Shaping Service, which went live in September 2025. Rather than relying on a small sample, it calculates load shapes from validated half-hourly data now flowing in from across the market and applies the shape for the relevant load-shape category.

This is worth being clear about, because it is widely misreported. MHHS itself does not require you to have a smart meter. All meter types are included: smart, advanced and traditional. What a traditional meter gets is a new, market-wide method of estimating its half-hourly consumption. What it does not get is your actual data.

The reason for the reform is cost. Ofgem’s case rests on flexibility: if customers can be rewarded for moving consumption away from the busiest periods, the system needs less generating capacity and less network reinforcement, and everyone’s bills carry less of that cost. Rewarding it first means being able to see it, and an estimated profile cannot.

Where the Rollout Has Reached

Migration is running supplier by supplier, in waves, across an 18-month window.

Date	Milestone
September 2025	Elexon’s new central systems, including the Load Shaping Service, go live
October 2025	Migration of metering points begins
July 2026	Half of all industry metering points migrated
28 October 2026	All suppliers must be able to operate under the new arrangements
7 May 2027	Full migration complete
1 April and 2 July 2027	Settlement timetable shortens to seven months, then four

Elexon expects around 80% of metering points to have migrated by that October 2026 date, though the milestone itself is about supplier readiness rather than a migration target. Your supplier manages when your meters migrate, and may write to tell you it has happened.

What It Means for Your Business

The migration does not rewrite your contract

Moving your meter into half-hourly settlement does not, by itself, change the rates you have agreed for the remainder of your current contract, and suppliers have been clear on this point. What can change separately is metering and data services: some suppliers are updating those charges to reflect the additional data handling MHHS involves, and itemising them on bills rather than bundling them. Any supplier correspondence about metering charges is worth reading properly.

You are not required to have a smart meter

Government statistics show that 64% of meters at smaller non-domestic sites in Great Britain were smart or advanced at the end of Q2 2025. The rest are settled on an estimated shape. That estimate is better than it used to be, but it is still an estimate, not a record of what your business actually did. Tariffs priced on what you actually use need a meter that records it.

Your supply number has already changed

The supplementary ‘top line’ of your electricity supply number (the MPAN) changed across the market in September 2025. Specifically, the old 3-digit Meter Timeswitch Code (MTC) expanded into a 4-digit Standard Settlement Configuration (SSC) ID, and the Line Loss code became the DUoS Tariff ID. While your core 13-digit supply number (the bottom row) remains identical, your invoice reference data now carries this extra digit. If your finance team uses automated bill-validation software across a multi-site portfolio, ensure your systems are configured to reconcile the updated 9-character top row cleanly.

Suppliers will have a clearer picture of when electricity is used

Ofgem anticipated exactly this when it approved the reform, stating that MHHS “will place the right incentives on retailers to develop and offer new tariffs and innovations that encourage and enable more flexible use of energy, such as time of use tariffs”. Ofgem’s business case put the net benefit to consumers at between £1.6 billion and £4.5 billion over the period to 2045.

MHHS is not an energy monitoring service

It is a change to market settlement. It does not hand your business a consumption dashboard. It builds the infrastructure on which better-targeted tariffs and flexibility products can be offered, and leaves it to you to be ready for them.

What to Do Now

You do not need to arrange your migration. A few things are worth checking anyway, and all of them put you in a stronger position at your next renewal. Your dedicated consultant at Smarter Business can help with any of them.

1. Find out what meter you have

Smart, advanced or traditional. Your supplier or your broker can confirm it, and it determines whether your settlement data is based on actual consumption or an estimated shape.

2. Find out which migration wave you are in

Waves run to May 2027. Your supplier will know when yours is due, and your dedicated consultant can find out for you.

3. Get hold of your half-hourly data

If you have a smart or advanced meter, suppliers have been required since December 2022 to give you and any third party you nominate, such as your dedicated consultant, free access to up to 12 months of historic consumption data. You may first need to give permission for your data to be shared at half-hourly granularity.

4. Look at what you use when you are closed

Overnight and weekend consumption is where equipment left running shows up, along with heating or cooling set to hours you no longer keep, and unusual changes in baseload that may be worth investigating. Your bill shows totals, not the shape of your day.

5. Check your bill validation still reconciles 

Make sure your invoice checks still match correctly against the new supply number format.

6. Ask what is available at renewal, then judge it on total cost

Time-of-use and multi-rate tariffs already exist, from simple day and night rates to multi-band pricing, and more options are expected to become available as MHHS progresses. A tariff with attractive off-peak rates only saves money if your usage genuinely falls in those periods, and your own data is what tells you whether it does.

Get Ready for Your Next Energy Renewal

MHHS is not something most businesses need to act on, but it changes the questions worth asking at renewal. Half-hourly settlement is not new for larger sites. Extending it across the market gives the industry a much more granular view of when electricity is used, and more scope to build tariffs around it. Businesses that can see their own usage will be better placed to judge what they are offered.

At Smarter Business, we help businesses understand the market they are buying in. If you would like a clear view of where your business sits ahead of your next renewal, get in touch.

MHHS FAQs

Do I need a smart meter for MHHS? 

No. MHHS covers all meter types, including traditional meters. Without a smart or advanced meter, your consumption is settled after migration using a half-hourly shape calculated by Elexon’s Load Shaping Service rather than your own actual data.

Will MHHS increase my business electricity bills? 

MHHS migration does not, by itself, change the agreed rates in your existing contract. Two things can change separately: metering and data service charges, depending on your supplier and contract, and pricing at renewal, which can increasingly reflect when your business uses electricity rather than only how much. That may work for or against you. Across the market, more accurate settlement is expected to lower costs over time, but not as a guaranteed saving on any one bill.

Do I need to do anything? 

You do not need to arrange your migration; your supplier handles it. The useful steps are voluntary: find out what data your meter produces, and use it.

Does MHHS apply to business gas? 

No. MHHS is a reform of the electricity market only. It does not affect gas metering or billing.

Will I need a separate agreement for my meter or data handling?

For smaller business supplies, metering and data services can continue to be managed directly through your supplier under updated MHHS industry roles, however, you can opt to get your broker to review offers for you. Larger half-hourly operations retain the option to appoint independent, specialist meter operators (MOP) and data collectors to maintain bespoke data control.

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