MHHS (Market-wide Half-Hourly Settlement)
MHHS is the industry programme that moves electricity settlement to half-hourly data for everyone.
What it is
Market-wide Half-Hourly Settlement (MHHS) changes how the electricity market works out who owes what. Instead of estimating when many customers use power, it uses half-hourly data. It is an industry change, not a product you buy.
Where you will see it
- In supplier letters about meter changes or data.
- In changes to how your settlement details are recorded, which can affect the top line of your MPAN.
Timeline
- Migrations began on 22 October 2025.
- About 80% of meters were expected to be migrated by October 2026.
- Full implementation is due in May 2027.
By 17 June 2026, more than 11.3 million migrations had been completed, about a third of metering systems.
Why it matters
For most small businesses, little changes day to day. The big shift is that billing and settlement increasingly use real data, which should mean fewer estimates, and in time more tariffs that reward using power at cheaper times. Old roles like the Data Collector and Data Aggregator are being reshaped. See does MHHS change my bill and MHHS for businesses.
Example
A shop on a standard meter is migrated. It keeps the same supplier and contract, but its meter data now flows into settlement in a new way.
What you should do
Nothing special is needed. Keep your contact details up to date with your supplier, submit readings if asked, and check that your next bill is sensible. If a bill looks wrong after a meter change, raise it with your supplier first, then follow the route in energy disputes and the Ombudsman.
Related terms
Common questions on this topic
Sources
General information only. Energy prices, rules and supplier terms change; check the latest position with your supplier, Ofgem or the Energy Ombudsman before you act.