Back-billing on a prepayment meter

Great Britain · Rules checked 24 October 2026 · Not legal advice

Free tool: Back-billing calculator. Enter the bill date and the period charged to find the 12-month line.

The back-billing rule isn't just for people who get bills. It covers any attempt to recover charges, and the licence condition says so: it includes recovering charges "via a Prepayment Meter".

When prepayment back-bills happen

• The meter wasn't updated with the right tariff or standing charge, so you were undercharged.
• A smart prepayment meter wasn't set up correctly.
• Debt is suddenly added to the meter to recover past charges.

Ofgem's 2020 open letter specifically criticised suppliers that wrongly believed the rule didn't apply to prepayment customers, and listed "failing to update a prepayment meter with the correct tariff or balance" as a cause of back-bills.

What to do

1. Ask the supplier, in writing, what the debt is for and which dates it covers.
2. If any of it relates to energy used more than 12 months before it was added, ask for that part to be removed (SLC 21BA). The calculator shows the line.
3. Ask for any recovery rate to be set by what you can afford (SLC 27.8). See repayment plans.

If the debt is from a previous occupant, that's a different problem: see bills for someone who lived there before.