What Does MID Approved Mean? Billing Tenants and EV Drivers From a Sub-Meter

The short answer: a MID-approved electricity meter is a type that has been independently tested and certified as accurate enough to charge people by. If you bill anyone for electricity by the unit, such as a tenant, a sub-let unit, a holiday let or an EV driver, the meter needs to be an approved type, and in practice that means a MID-approved meter. If you only want to see your own usage, you don't need one, though it costs little extra.

Where MID comes from

MID stands for the Measuring Instruments Directive, the European law that sets accuracy rules for instruments used to charge people, from petrol pumps to electricity meters. In Great Britain the same rules sit in the Measuring Instruments Regulations 2016 (MIR), so GOV.UK now calls these "MIR approved" meters. A meter carrying the MID marks still qualifies, and newer designs may carry the UKCA mark instead. Before a meter design can carry the approval, an independent assessment body tests it against the European accuracy standard for electricity meters, EN 50470-3.

The approval covers the meter design and its manufacture. It says nothing about how well a meter has been installed, which is why fitting it properly matters too.

When you need a MID-approved meter

• Landlords recharging tenants for electricity used in a flat, a room in a shared house or an annexe.
• Commercial landlords recharging units on a shared supply.
• EV charge points where drivers pay for what they use, including at holiday lets and workplaces.
• Farms, marinas, caravan and camping sites charging pitches or berths for electricity.
• Anyone splitting a bill with another household or business by meter reading.

You don't need one to monitor your own solar generation, find out what your heat pump costs to run or build an energy dashboard. Plenty of people buy one anyway, because its accuracy is independently tested and the price difference is small.

How to tell a meter is MID approved

An approved meter carries three marks together, usually on the front:

• the CE or UKCA mark;
• a capital M with two digits inside a rectangle, the digits showing the year the marking was applied, so M24 is a 2024 meter;
• a four-digit number identifying the body that assessed it.

You will also see an accuracy class. MID uses three: A, B and C, with C the most accurate. If a meter doesn't show these marks, it isn't approved for billing, whatever the listing says.

The official guidance is on GOV.UK: MIR approved gas and electricity meters.

What you're allowed to charge

The meter decides how many units you charge for. The price is a separate question. If you resell electricity to someone for domestic use, Ofgem's maximum resale price rules say you can't charge more per unit than you pay your own supplier, plus a fair share of the standing charge. You can't add a profit margin.

Ofgem's current guidance dates from 2005, and Ofgem began reviewing the rules in October 2025, so check its latest guidance before you set a price. The meter is the easy part: an approved meter gives you figures both sides can trust.

Practical tips for billing from a sub-meter

• One meter per supply you charge for. Don't try to split one reading between two tenants.
• Put it where it can be read. A tenant who can check the display is a tenant who doesn't dispute the bill.
• Photograph the reading at the start and end of every tenancy or booking.
• Keep the terminal covers on and sealed once it's installed, so nobody can question whether it's been tampered with.
• Read it remotely if you have several. Meters with Modbus RS485 can be read by Home Assistant or a building system, so you don't need to visit each one.

MID-approved meters from OmniKit

All the Eastron meters OmniKit stocks are MID approved and read over Modbus RS485:

• the Eastron SDM230 for single-phase supplies up to 100A, MID Class B;
• the Eastron SDM72D-M for three-phase supplies up to 100A, MID Class B;
• the Eastron SDM630MCT for larger three-phase supplies using clip-on CT clamps, MID Class B or C depending on the model.

Not sure which suits your supply? Our guide Which Eastron meter do I need? walks through it.

Common questions

Can I bill a tenant from a smart plug or a clamp-on energy monitor?
No. Those are useful for seeing what an appliance uses, but they aren't approved for billing. Use a MID-approved meter wired into the circuit. Our guide Shelly or Eastron for Home Assistant compares a popular clamp-on monitor with a MID meter.

CE or UKCA: does it matter?
In Great Britain an approved meter can carry either mark alongside the M marking and the body number.

Does MID Class B mean the same as Class 1?
They are two different standards describing similar accuracy. Class 1 is the international (IEC) rating, and MID Class B is the European billing standard. Eastron's SDM230 and SDM72D-M carry both.

Do I need an electrician to fit one?
Yes. A billing meter connects to mains wiring, so it must be installed by a competent person to the current UK wiring regulations.

Questions about a particular job? Email customersupport@omnikit.co.uk and we'll help you choose.