How to dispute an energy back bill in the UK (Ofgem 12-month rule)
Not legal advice. This article is general information and a pointer to letter templates only. Claim Helper does not act as your solicitor, representative, or claims management company. Outcomes are not guaranteed. Accurate charges for the last 12 months may still be payable. Official guidance: Ofgem — What to do if you get a back bill.
A back bill is when your electricity or gas supplier asks you to pay for energy you already used, but which was not accurately charged at the time — for example after a billing mistake or a meter problem.
Step 1: Check the dates on the bill
Look at the date of the bill or charge recovery notice, the earliest date the charges claim to cover, and whether the total includes usage more than 12 months before the bill date. Ask the supplier for a detailed breakdown if it is unclear. The Energy Ombudsman recommends checking billing dates and requesting a breakdown: What is back billing?.
Step 2: Apply Ofgem’s 12-month rule
Ofgem says domestic and microbusiness customers generally do not have to pay for energy used more than 12 months ago if:
- you have not had an accurate bill for it before; and/or
- you have not been told what you needed to pay through a statement of account before; and/or
- your Direct Debit was previously set too low to cover what you needed to pay
Source: Ofgem back bill page.
There is an exception if you have acted unreasonably (Ofgem examples include blocking meter access, ignoring payment requests, or stealing energy). See: Ofgem 12-month back-billing rule explained.
Step 3: Complain to the supplier in writing
Contact the supplier right away. Ask them to confirm the charge recovery date and send a full breakdown; apply the back-billing rules and write off older unbilled consumption where the rules apply; refund any money taken in error for that older period; recalculate any balance for the last 12 months only; and offer an affordable payment plan if a legitimate recent balance remains and you are struggling.
Prefer the supplier’s complaints process. Keep copies and any complaint reference.
Use our free preview generator: Energy back-billing letter generator. Citizens Advice also publish a related template: Complain to a supplier about back-billing.
Step 4: Wait eight weeks — or escalate sooner on deadlock
Ofgem states that your supplier should try to fix problems within eight weeks. You can escalate to the Energy Ombudsman if eight weeks have passed without a satisfactory resolution; or you receive a deadlock / final decision letter; or you cannot agree how to fix the problem.
Sources: Ofgem — Complain about your energy supplier; Energy Ombudsman process.
Ofgem does not decide individual billing disputes. The Ombudsman is the free independent redress scheme for supplier complaints that stall.
Step 5: Register with the Energy Ombudsman
Create a case online (fastest), or use phone / email / post as described on the Ombudsman site: Creating a case. Upload the back bill, earlier statements, meter readings, and your complaint correspondence.
DIY letter template
- Interactive preview: energy-generator.html
- Project template:
templates/energy-back-billing-complaint.md - Phase plan:
LAUNCH_PLAN_ENERGY.md
Sources
- https://www.ofgem.gov.uk/your-energy-supply/your-energy-bill/what-do-if-you-get-back-bill
- https://www.ofgem.gov.uk/your-energy-supply/problems-your-energy-supply/complain-about-your-energy-supplier-or-network-operator
- https://www.energyombudsman.org/advice-for-consumers/what-is-back-billing
- https://www.energyombudsman.org/our-process
- https://www.citizensadvice.org.uk/consumer/template-letters/letters/energy-letters/complain-to-a-supplier-about-back-billing/