What is a catch-up bill, and do I have to pay it?

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.

A catch-up bill (or back-bill) arrives when your supplier recalculates your account. Usually it has received an actual meter reading after months of estimates, fixed a smart meter, or found a billing error, and now says you owe the difference.

Common causes

• Bills based on estimated readings that were too low.
• A smart meter not sending readings.
• A Direct Debit set too low for what you were using.
• Billing for the wrong meter, or a new account that was never billed after you moved in.

Which parts you have to pay

Ofgem says you need to pay any accurate bill, including a back-bill, but the 12-month rule limits how far back it can go. Energy used in the 12 months before the bill date is normally payable. Energy used before that usually isn't, unless you were billed correctly at the time or blocked accurate billing.

Checks to make

1. Is the latest reading right? Compare it with a dated photo of your meter.
2. What is the earliest date charged? Put it into the back-billing calculator.
3. Ask for a breakdown: readings used (actual or estimated), unit rates, standing charges and dates. Suppliers must explain how a bill was worked out if you ask (SLC 21B.7).
4. If you can't pay what's left in one go, ask for an affordable repayment plan.

Questions