Market-wide half-hourly settlement

Status: LawSettlement has historically used estimated profiles for smaller meters, with actual half-hourly data used only on larger supplies. Market-wide half-hourly settlement replaces that with settlement on actual consumption for every meter.

Migration began on 22 October 2025. Around 80 per cent of meters are expected to have migrated by October 2026, with full implementation in May 2027.

Settlement completion currently takes around fourteen months. Under the new arrangements it reduces to about four.

Ofgem has estimated a net consumer benefit in the region of £1.6bn to £4.5bn. That is a system-wide estimate rather than a saving any individual business should expect, and we would not present it as one.

The effect that matters for a specific site is more mundane and more useful: consumption data becomes available at half-hourly granularity on supplies where it previously did not exist.

• Overnight baseload becomes visible on smaller sites. Plant running through closed hours is one of the most common findings and it cannot be seen on a quarterly read.
• Estimates reduce. A meter settled on actual consumption produces fewer corrections later.
• Comparisons become sounder. Site against site and year against year mean more when both sides rest on actual data.
• Time of use pricing becomes meaningful. A tariff that varies through the day is only worth having if you can see when you use energy.

Very little, in terms of the migration itself. It happens through the industry rather than through you, and your supplier and meter operator handle it.

What is worth doing is being ready to use the data once it exists. A site that gains half-hourly data and never looks at it has gained nothing.