Half-hourly settlement means the electricity your business uses will be matched to its real cost in each 30-minute slot, instead of an estimated profile. Every meter in Great Britain is being moved across, with migration due to finish on 7 May 2027. Your unit rate won't change overnight because of it, but the way suppliers price contracts may.
What is "settlement", and why does it matter to a business?
Settlement is the behind-the-scenes process that works out how much electricity each supplier's customers used, and when, so suppliers pay the right wholesale and system costs. It isn't your bill, but it shapes what your supplier pays to serve you.
Under the old arrangements, most smaller business and household meters were settled using standard profiles. These are assumptions about when a typical customer uses power, applied to monthly or estimated readings. Elexon, which runs the settlement process, says settlement under the old arrangements took 14 months to complete. The target under the new system is four months.
Half-hourly settlement replaces the assumptions with actual consumption measured every half hour.
Isn't half-hourly already the norm for businesses?
For larger sites, yes. Ofgem's 2021 decision says the reform builds on rules that already required half-hourly settlement for medium to large non-domestic customers. Smaller businesses and households could choose it, but few did.
What's new is that it becomes market-wide. That includes the smaller business sites on smart or older meters that were settled on profiles.
What are the key dates?
As of October 2026, Elexon's published timetable is:
| Date | What happens |
|---|---|
| 22 Oct 2025 | Suppliers start moving meters to half-hourly settlement |
| By Oct 2026 | Elexon expects about 80% of meters to be in the new arrangements |
| 28 Oct 2026 | All suppliers must be able to handle meters under the new arrangements |
| 7 May 2027 | All meter migrations complete |
| 2 Jul 2027 | Cutover to the shorter settlement timetable; old and new run side by side until then |
The programme has slipped before. Ofgem's original 2021 plan was to finish by October 2025, and Ofgem agreed a 6.5-month delay in 2024. In April 2025, Ofgem and the Energy Secretary wrote to supplier chief executives saying no further delays would be accepted.
Will your business electricity bill go up or down?
Neither Elexon nor Ofgem says the move itself changes any individual bill. What it changes is the information suppliers have.
Ofgem says suppliers will get more accurate data on each customer's use and the cost of serving them through the day. Ofgem expects that to encourage time-of-use tariffs, automation and battery storage. It estimated in 2021 that the reform would save consumers £1.6 billion to £4.5 billion by 2045. That's a system-wide figure, not a promise to any one business.
In practice, the effect on you depends on when you use power:
- Sites that use a lot at peak times may find suppliers price that more accurately, which could mean less "averaging" in their favour.
- Sites that use more overnight or can shift use (refrigeration, batch processes, EV charging, storage) may be offered tariffs that reward it.
These are possibilities, not certainties. Contract offers will vary by supplier.
Do you need a new meter?
Elexon says half-hourly settlement applies to sites with meters that can record use in 30-minute slots, which smart meters do. Its timetable covers smart meters, advanced meters (normally used by larger businesses) and non-smart meters, so suppliers are expected to migrate all of them.
If you still have an older meter, ask your supplier how your site will be settled and whether a smart or advanced meter is planned. A meter that gives your own half-hourly data also helps you see where energy is going. Elexon lists that visibility of usage patterns as a benefit for businesses.
What should you check in your contract?
The reform changes how suppliers' costs are worked out, so it's worth reading the pricing clauses before you sign or renew:
- Fixed or pass-through? Check whether your unit rate is fully fixed, or whether some costs can be passed through and changed during the contract. Our guide to fixed, flexible and deemed contracts explains the difference.
- Time-of-use rates. If you're offered day/night or time-banded prices, check which hours each rate covers and model your own usage against them.
- Data and meter clauses. Look for anything that depends on your meter type or on you allowing access to half-hourly data.
- Renewal timing. Many contracts renewing between now and mid-2027 will be priced while migration is still happening. The renewal checklist covers notice periods and when to start.
If a term is unclear, ask the supplier or broker to explain it in writing before you agree. The business energy glossary explains MPANs and other jargon you may see.
How can you use this to your advantage?
Half-hourly data is useful even before any tariff changes. If you know when your site draws power, you can spot equipment running out of hours, compare quotes on a like-for-like basis and judge whether a time-of-use offer suits you.
To check whether your current price looks reasonable, use the free estimator and the business electricity prices guide. For help reading the lines on your bill, see how to read a business energy bill.
This is general information, not legal or financial advice.
What to do next
- Find your MPAN on your bill and ask your supplier whether your meter has moved to half-hourly settlement yet.
- If you don't have a smart or advanced meter, ask whether one is planned and how your site is settled until then.
- Ask for your half-hourly usage data, or check your supplier's online account, and note when your peak use happens.
- Before renewing, check which parts of the price are fixed and which can be passed through.
- If you're offered time-of-use rates, test them against your actual half-hourly usage before you sign.
- Put 7 May 2027 in your diary as the date all meters should be migrated.