What is half-hourly settlement and MHHS?

Half-hourly settlement accounts for electricity in 30-minute periods in the market, rather than describing how often your supplier invoices you [S1]. Market-wide Half-Hourly Settlement, or MHHS, extends the new arrangements across the market. The programme says migration runs from October 2025 until May 2027 [S2]. Ask your supplier about your particular meter and data services. Checked October 2026.

Last checked 19 October 2026

What does half-hourly settlement mean for your site?

Half-hourly settlement is electricity-market accounting using half-hour periods. A settlement period lasts 30 minutes [S1]. Market-wide Half-Hourly Settlement (MHHS) is the programme moving supplies into new settlement arrangements [S2], [S4].

Why it matters for your site: your supplier and metering arrangements may change even when the equipment on the wall looks familiar. Request confirmation of your supply’s migration status, appointed services and available data.

Keep settlement, meter readings and retail prices as separate questions. Ofgem describes the reform as enabling new products that reward flexible energy use; that does not establish the price in your existing contract [S4].

Where does the migration timetable stand?

The programme’s current migration page says migration started in October 2025 and runs until May 2027 [S2]. Ofgem’s approved CR055 plan distinguishes migration completion in May 2027 from the new settlement timetable in July 2027 [S3]. These are programme dates, rather than confirmation that your particular supply has migrated.

Ask your supplier for the effective date against your Meter Point Administration Number (MPAN). Do not infer that all your premises have moved because another site has received a notice. The programme coordinates suppliers and agents through migration planning and execution stages [S2].

What should you request for a charging project?

Ask for a downloadable consumption file, the units, timestamp convention and actual or estimated indicators. Request an explanation of any missing periods before using the file to size chargers, solar or batteries.

For illustration, assume a depot imports 10 kilowatt-hours (kWh), a measure of energy, during a half-hour. Average power = 10 ÷ 0.5 = 20 kilowatts (kW). These are assumed inputs, not a forecast or a retail price.

Read half-hourly metering and DUoS charges for billing components and meter operators for responsibilities. Our business electricity data supplies market context, not your contract terms.

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