Back billing complaint template for UK energy bills
Use this when the supplier has sent old charges or a catch-up bill and you need a focused written complaint instead of a vague objection.
Best next steps
Before using the template
Bill dates
Identify the statement date and supply period.
Old period
Highlight charges for older usage.
Reading history
Separate actual and estimated readings.
Requested remedy
Say whether you want charges removed, rebilled or explained.
Copy/paste back billing wording
Subject: Back billing review request Please review my recent energy bill because it appears to include charges for an older period. Please identify any charges relating to energy used more than 12 months before the bill date, explain whether the back billing rules apply, and remove or correct any charges that should not be billed. Please also provide the reading history used, the bill dates, the supply period covered and a written explanation of how the balance was calculated. I have attached the relevant bill(s), readings and account history for review.
Do not weaken the complaint
- Do not complain about every issue at once.
- Do not say only that the bill is unfair.
- Do not leave out dates and readings.
- Do not accept a payment plan until you understand whether older charges should remain.
Use after this
The letter, written out in full
Copy, fill in the square brackets, send by email
Numbering the requests matters more than the tone. A numbered list is harder to answer with a paragraph of general reassurance, and if it goes to the Ombudsman, it shows exactly which questions the supplier declined to answer.
The rule itself, in one paragraph
Standard Licence Condition 21BA is the back-billing rule for domestic customers. It says a supplier must not charge you for gas or electricity used more than 12 months before the date of the bill, where the supplier is the reason you were not billed accurately during that period. It has applied to every licensed supplier in Great Britain since 1 May 2018. Microbusinesses get the same protection under SLC 7A.
Two things in that sentence do most of the work, and most complaints are lost on them:
- “12 months before the date of the bill.” The clock runs backwards from the bill, not from when you noticed, not from when the meter was last read, and not from when you first complained. A bill dated 3 September 2026 cannot properly charge you for energy used before 3 September 2025 if the supplier was at fault.
- “Where the supplier is the reason.” The protection is about supplier failure. If the supplier can show you obstructed accurate billing — refused meter access, ignored repeated reading requests, or behaved in a way the rule calls manifestly unreasonable — the protection can fall away for that period.
Source: Ofgem, Modification of the electricity and gas supply licences to introduce rules on backbilling, in force 1 May 2018. Always check the current licence text before quoting a condition number to a supplier — conditions are amended.
When the protection does not apply
Suppliers do sometimes have a real answer. It is worth knowing which ones are legitimate, because arguing against a valid exception wastes the eight weeks you need before you can escalate.
| What the supplier says | Does it hold up? | What to ask for |
|---|---|---|
| “You blocked access to the meter.” | Potentially valid. This is the main exception in the rule. | Dates of every access attempt, the letters or texts sent, and what response was recorded. |
| “You never gave us readings.” | Only if they asked and you did not respond. Silence from the supplier is their failure, not yours. | The reading-request history, and your own submitted readings from the app or account. |
| “This is a catch-up bill, not a back bill.” | Often true and often the real answer. | A period-by-period breakdown, so you can see which side of the 12-month line each charge sits on. |
| “The rule does not apply because you changed supplier.” | Weak. The obligation follows the supplier that failed to bill. | Which licensed entity billed each period, and the final statement from the losing supplier. |
| “There was a meter fault, so we could not bill.” | A fault is normally the supplier's problem to detect and fix. | When the fault was first flagged in their system and what they did about it. |
| “It was a billing system migration.” | Not an exception. An internal IT project is supplier fault. | Written confirmation that the delay was caused by their systems. |
Notice the pattern: almost every valid exception depends on something the supplier must be able to evidence. Asking for that evidence, in writing, is the whole move. A supplier that cannot produce a record of asking you for readings has effectively conceded the point.
A worked example with real numbers
Abstract advice loses arguments. Here is the arithmetic a supplier has to be able to reproduce, using the Ofgem price cap rates for 1 July to 30 September 2026 (electricity 26.11p per kWh plus a 57.19p daily standing charge).
| Period on the bill | Units charged | At 26.11p/kWh | Standing charge | Line total |
|---|---|---|---|---|
| Apr 2024 – Mar 2025 older than 12 months | 2,900 kWh | £757.19 | 365 × 57.19p = £208.74 | £965.93 |
| Apr 2025 – Mar 2026 | 2,750 kWh | £718.03 | 365 × 57.19p = £208.74 | £926.77 |
| Apr 2026 – Aug 2026 | 950 kWh | £248.05 | 153 × 57.19p = £87.50 | £335.55 |
On a bill dated August 2026, the first row is the one that matters. It is roughly £966 of a £2,228 balance, it sits outside the 12-month window, and if the supplier failed to bill accurately during it, that line should come off. The other two rows are almost certainly payable — and saying so in writing is what makes the rest of the letter credible.
Why the standing charge line matters. People argue about units and forget that a full year of standing charge at 57.19p a day is £208.74 on electricity alone, before a single kWh. If a protected period is removed, its standing charges go with it. Ask for that explicitly, because it is frequently left on the bill.
Rates shown are the Ofgem cap averages for direct debit customers in England, Scotland and Wales, including VAT. Your region and payment method change them. Use the kWh to cost calculator with the rates printed on your own bill.
Frequently asked questions
Can I use this for any catch-up bill?
Use it when there is a real old-period question. For a normal catch-up bill, start with the catch-up bill page.
Should I attach evidence?
Yes. Attach bills, readings, photos and contact history.
Can I use this template for any catch-up bill?
Only where part of the balance is for energy used more than twelve months before the bill date. If everything falls inside twelve months it is a catch-up bill, the back-billing rule does not apply, and quoting it makes the rest of the letter look uninformed. Use the catch-up bill page instead.
What should I attach?
The full bill PDF, your own timeline of what arrived when, and any evidence that you submitted readings or chased for a bill. Screenshots of reading submissions with dates are the single most useful attachment.
What if they refuse?
Ask which exception they are relying on and for the evidence behind it — normally the record of reading requests or attempted meter access. If they cannot produce it, escalate to the Energy Ombudsman at eight weeks, or immediately on a deadlock letter.