MHHS: what market-wide half-hourly settlement means for your business

Market-wide half-hourly settlement (MHHS) is an industry change to how electricity suppliers are charged for the power their customers use. It is being delivered by suppliers and the settlement system, and for most small businesses there is nothing you must do. It matters because it makes your half-hourly usage more important, and it may bring new kinds of tariff.

What "settlement" means

Every half hour, the amount of electricity generated and supplied across Great Britain has to be reconciled. That reconciliation is called settlement, and it decides which supplier owes what to the system. Until now, if you had an ordinary meter, your supplier was settled using your annual use spread across the day according to a typical profile for your profile class. Elexon, the company that runs settlement, describes this as estimating half-hourly use from a class shape. Larger sites (profile classes 5 to 8) have been settled on their actual half-hourly data since 2017.

MHHS extends actual half-hourly data to everyone. Your meter, whether it is a smart meter or not, will be settled on real use as far as the data allows, rather than on a shape.

The timetable

When	What
22 October 2025	Suppliers began migrating customers' meters to MHHS
17 June 2026	More than 11.3 million migrations done, about one third of Britain's metering systems
October 2026	Suppliers expected to have migrated about 80% of meters, subject to the programme plan
28 October 2026	Milestone: all participants must be qualified to take part
May 2027	Full implementation

These come from Elexon's update of 17 June 2026; the October 2026 figures were expectations at that time, not confirmed results. Dates in a large programme can move, so check Elexon's pages for the latest position.

What changes for a small business

Probably nothing you have to do

Elexon's published material is aimed at industry participants and does not tell customers to take action. If your supplier contacts you, read what it says, but do not assume a request to book an engineer is from a legitimate party; check with the supplier on a number from your own bill. Our guide to cold calls about business energy covers common scams.

Your meter may change class

You might notice your MPAN now starts with 00, meaning half-hourly settled, where it once started 03 or 04. It is a settlement label, not a sign that you have been put on a larger-business tariff. If it prompts a question, see why was my business moved to a half-hourly meter and does MHHS change my bill.

More accurate data, fewer estimates

Half-hourly data should make estimated bills less common where a smart meter reports automatically, although no specific change to small-business bills has been published. See estimated business energy bills.

Possible new tariffs

Elexon describes MHHS as supporting tariffs that better reflect real-time system conditions and reward flexible use. That is a stated aim, not a guarantee of products or savings. If a supplier offers a time-of-use deal, work out whether you can actually move use before accepting.

What does not change

• Your contract. Fixed prices stay fixed; MHHS does not let a supplier alter a fixed rate. See can a supplier change my fixed price.
• Your right to switch. Settlement is behind the scenes.
• Who you complain to. Supplier first, then the Energy Ombudsman if unresolved (see energy disputes and ombudsman).

The scale of the data

One meter produces 48 readings a day, so 365 × 48 = 17,520 a year. Elexon says that once MHHS is complete it will process up to 500 billion half-hourly readings a year. That scale is why the migration has been phased by supplier.

How it relates to smart meters

Smart meters are the main way half-hourly data will reach the system for smaller sites, but they are separate programmes. The smart meter rollout has its own dates: a duty on suppliers from 1 September 2027 to include smart or advanced meter terms in new fixed-term non-domestic contracts. MHHS can run on a non-smart meter (with estimated half-hours), but accuracy gains need smart data.

Worked example

A florist uses 18,000 kWh a year. Spread across all 17,520 half-hours in a year, that is 18,000 ÷ 17,520 = about 1.03 kWh per half-hour on average. Under profile settlement the market assumes a typical shape for a class 3 business, whatever the florist actually does. With actual half-hourly data, the market sees the real pattern, for example a flat 0.3 kWh overnight for the cold room and bigger daytime use. Whether that changes the florist's bill depends entirely on the tariff: most small-business tariffs use a single unit rate, so the direct effect on price may be small. What the florist gains is the data, which shows that the overnight 0.3 kWh × 2 half-hours per hour × 14 closed hours = 8.4 kWh a night is the cold room, not waste. All figures are illustrative.

Questions owners ask

Do I need a new meter?

Not because of MHHS alone. Settlement can use readings from the meter you have, although a smart meter gives more accurate data. See business smart meters.

Will it cost me anything?

We found no published charge to customers for the migration. If an invoice cites MHHS, ask the supplier to explain the charge and where your contract allows it.

Is this the same as the half-hourly meter I was told to get?

No. A half-hourly meter is equipment; MHHS is the settlement process. Our half-hourly meters guide covers the equipment side.

Who is responsible for what

Your supplier decides when to move your meter point onto the new arrangements, as the programme is supplier-led. Elexon says eleven suppliers were actively migrating at its June 2026 update, which means timing varies. Meter operators and data collectors also have to be ready, which is why the milestone of 28 October 2026 for all participants to be qualified matters. If your supplier is small or new, ask where it is on its migration plan, particularly if you are about to sign a long contract.

Next steps

1. Check the first two digits of your MPAN today and note them.
2. If your supplier writes about MHHS, keep the letter.
3. Ask for your half-hourly data if you have a smart meter and want to look for waste.
4. At renewal, ask whether any new tariff rewards flexible use, and compare it against a normal fixed deal.