Check the bill first. Challenge it with evidence second.
BillDecoded is a utility-led dispute-prep site for UK energy bills: calculate the numbers, identify the issue, gather evidence and send a clearer written request.
Start with the problem
Direct debit jumped
Check whether the monthly amount looks reasonable before accepting or disputing it.
Direct debit calculatorChallenge wordingWrong meter reading
Use photos, serial numbers and reading dates to ask for a corrected rebill.
Reading guideTemplateBack bill or old charges
Separate back billing from catch-up bills before complaining.
RulesComparisonRates and bill maths
Use the correct unit rate, standing charge, region and payment method.
Rate referencekWh calculatorSupplier-specific issue
Use supplier guidance only after choosing the right issue type.
British GasOctopusHow BillDecoded works
| Step | Goal | Useful page |
|---|---|---|
| 1. Diagnose | Identify the exact problem, not just “bill too high”. | /articles/ |
| 2. Calculate | Sense-check the number against readings, rates or forecast. | /calculator/ |
| 3. Gather evidence | Build a bill, reading and message timeline. | /checklist/ |
| 4. Send wording | Ask for a specific correction in writing. | /energy-bill-complaint-letter-template-uk/ |
| 5. Escalate cleanly | Use Ombudsman pages only when the supplier route is ready. | /energy-ombudsman-process-uk/ |
Evidence-led
Pages push users toward bill PDFs, meter photos, account balance data and written supplier responses.
Source-aware
Guides point back to official sources such as Ofgem, Energy Ombudsman and Citizens Advice where relevant.
Independent
BillDecoded is not affiliated with suppliers, the Ombudsman or regulators. It is informational, not legal advice.
Dated price-cap rates and current context
Before deciding a bill is wrong, it helps to know what right looks like. These are the Ofgem price cap figures for 1 July to 30 September 2026, for direct debit customers in England, Scotland and Wales, including VAT.
Rates vary by region — the spread between the cheapest and dearest region is about £145 a year for identical usage. See price cap rates by region for all fourteen. The next cap level, for 1 October to 31 December 2026, was announced on 26 August 2026.
The cap is not a cap on your bill. It limits the unit rate and the standing charge, not the total. Use twice the energy and you pay roughly twice as much. This is the single most common misunderstanding in UK energy billing.
Five rules worth knowing before you contact a supplier
Most people arguing about an energy bill do not know these, and every one of them changes what you can ask for.
| The rule | What it means for you |
|---|---|
| The 12-month back-billing rule Ofgem licence condition 21BA | A supplier cannot charge you for energy used more than 12 months before the bill date, where the supplier was at fault for not billing accurately. More |
| Direct debits must use the best information available | Not a stale estimate, and they must explain the basis when asked. More |
| Credit balances are refundable on request | Unless it is fair and reasonable to refuse. “We hold it for winter” is much weaker in April than in September. More |
| Eight weeks, then the Ombudsman | Free, independent, and binding on the supplier. A deadlock letter opens it sooner. Confirmed to drop to six weeks once legislated. More |
| You can ask for an independent meter test | The examiner's test is free, though your supplier may charge for removal if the meter turns out to be accurate. More |
The thirty-second check that solves most bills
Before anything else, look for a single letter on your bill.
An E next to the reading
The bill is estimated. Nobody read your meter — the figure is a guess based on history. Take a reading today, submit it, and ask for the bill to be reissued. That is the answer for a large share of the people who arrive here.
An A, C or S
Actual, customer-supplied or smart. Someone read the meter, so the units are probably right and the question is what used them — or whether the rates and days are correct.
Frequently asked questions
What should I check first on a high energy bill?
Start with readings, bill period, unit rate, standing charge and whether the bill is estimated or actual.
Can BillDecoded contact my supplier?
No. BillDecoded helps you prepare checks, calculations and wording. You send the complaint yourself.
Is this legal advice?
No. It is informational guidance for UK household energy bill checks and complaint prep.
What was the July–September 2026 price cap?
Ofgem’s revised typical-use headline for July–September 2026 was £1,663 a year for a GB dual-fuel household paying by direct debit. See the dated rate box above for the current period and the official regional table for your tariff.
How far back can my supplier bill me?
Twelve months, in the ordinary case. Ofgem's back-billing rule stops a supplier charging for energy used more than 12 months before the bill date where the supplier failed to bill accurately at the time.
What can I do if my supplier will not fix a wrong bill?
Raise a formal complaint and ask for the reference. Eight weeks later — or immediately if they send a deadlock or final response letter — refer it to the Energy Ombudsman. It is free, independent, and its decisions bind the supplier once you accept them.
Does BillDecoded charge for any of this?
No. Every guide, calculator and template on the site is free to use, and there is nothing to sign up for. The site carries advertising, and there are no affiliate links in its guidance — the outbound links go to Ofgem, Citizens Advice and the Energy Ombudsman because those are the sources, not because they pay anything.
Get the checklist and request bill updates
Download the checklist now. You can also leave your email to request future bill updates; this form records your request and does not send the checklist by email. Ask us to remove your address through the contact page.
Download the free checklist (PDF) — no email needed.