Market-wide Half-Hourly Settlement (MHHS) is a major reform of the UK electricity market that will move all electricity meters to settlement based on half-hourly data. The reform is designed to improve settlement accuracy and support a smarter, more flexible energy system.
Migration into the MHHS framework will take place between October 2025 and May 2027, with all electricity MPANs transitioning during this period.
As MHHS approaches, we have published a detailed set of FAQs explaining what MHHS is, what it is not, and what customers should expect as the market transitions. The FAQs cover key areas including migration, metering responsibilities, billing considerations and charging frameworks.