Back billing

What it is

Back billing happens when a supplier bills for energy that was used some time ago and never invoiced, such as after a faulty meter, wrong meter details or a long run of estimates. The bill can arrive as a large, unexpected "catch-up".

Where you will see it

Look for a bill covering a long past period, a note that readings were corrected, or a "revised bill" notice. Always compare it with your own meter readings.

The 12-month rule

Ofgem bans suppliers from back billing beyond 12 months. The ban applies to domestic customers and microbusinesses. It does not cover small businesses or larger customers. There are exceptions where the customer has blocked access to the meter, tampered with it or committed theft.

Why it matters

Your size decides your protection. Check whether you meet a microbusiness test for the fuel in question. If you do, you can challenge anything older than 12 months.

Example

Illustrative rates: a micro café is told it was under-billed by 3,000 kWh a month for 15 months, at 28.4p/kWh. The full claim would be 3,000 × 15 × £0.284 = £12,780. Capped at 12 months it is 3,000 × 12 × £0.284 = £10,224, so the supplier cannot collect the other £2,556. A small (non-micro) business could face the full amount.

The 12-month limit is not a right to ignore a valid bill within that window. Dispute it in writing and keep copies.

Related terms

See estimated reading, our back billing guide and how far back a supplier can back bill.