Ofgem back-billing rule (12 months): can you get a refund?

How to check eligibility and challenge a back bill (step-by-step)

Use this process before you pay a large catch-up bill. The aim is to (1) confirm dates and reads, (2) identify whether the supplier failed to bill correctly, and (3) ask for a recalculation that removes charges older than 12 months where rules apply.

1. Identify the unbilled period
   Find the dates the supplier says the bill covers (start and end). Mark anything older than 12 months from the date you were first correctly billed for that energy.
2. Gather evidence
   Take photos of your meter(s) now (include the serial number). Collect past bills, statements, meter reading submissions, emails/texts, and any move-in details (tenancy agreement completion date if relevant).
3. Check what caused the issue
   Common supplier-side causes: wrong meter serial number, misread meter type, estimated bills with no reconciliation, account set up incorrectly after a move, smart meter not communicating, or supplier failed to act on readings you provided.
4. Ask for a “back-billing review” in writing
   Request a recalculated bill applying Ofgem back-billing rules. Ask them to confirm: (a) when they first sent a bill based on an actual/accurate read, (b) why earlier bills were not accurate, and (c) which part (if any) they think is exempt.
5. If you’re worried about debt collection, request a hold
   If you dispute the bill, ask the supplier to place the account on hold while they investigate and to pause adverse credit reporting during the dispute (suppliers have complaints processes; outcomes vary).
6. Escalate if needed
   If unresolved after the supplier’s complaint process (or they issue a deadlock letter), you may be able to take it to the Energy Ombudsman. Citizens Advice can also help you understand your options.

Two realistic UK scenarios (with numbers)

These examples are illustrative. They assume a single property, domestic supply, and that the supplier’s billing failure is the reason older charges weren’t billed. Actual unit rates, standing charges, and billing dates vary by tariff and region.

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Quick self-check (60 seconds)

• Have you received no accurate bill for a long period (over a year)?
• Did you submit readings or try to resolve issues during that period?
• Were there errors like wrong meter details, estimated bills, or a failed smart meter?
• Were you ever asked for access/reads and did you cooperate?

Decision checklist: who this suits

• You’ve received a large catch-up bill covering more than 12 months.
• You have evidence you cooperated (read submissions, calls, emails, access attempts).
• The issue looks like a supplier/admin problem (meter details, failed billing, move-in errors).
• You want to stop overpaying and/or regain control by switching once accurate.

Who it may not suit (or needs extra care)

• You refused/blocked meter access repeatedly (supplier may claim an exception).
• You have a tenancy change with unclear liability dates (you may need landlord/letting-agent evidence).
• You’re dealing with debt, affordability issues, or vulnerability (you may need tailored support and repayment options).
• Your bill is recent; the main issue is accuracy, not the 12-month limit.

1) “Refund” vs “credit”

If older charges are removed, suppliers may apply a credit to your account rather than paying cash. If you’ve switched away or the account is closed, you can request a balance refund, but timings and processes vary.

2) You still owe for the latest 12 months

Back-billing doesn’t mean “free energy”. If you used energy in the last year and weren’t billed correctly, you can normally still be charged for that period (using accurate reads or fair estimates).

3) Exceptions (non-cooperation, obstruction, fraud)

If the supplier can show you prevented accurate billing (for example, repeatedly refusing access or withholding key information), they may argue the 12-month limit doesn’t apply. Ask them to evidence this.

4) Standing charges and tariff changes

Catch-up bills can include standing charges and multiple rate periods. Make sure the supplier uses the correct tariff rates for each date range, especially if you changed tariff or had price cap updates.

5) Smart meter data isn’t always treated as billing data

Even with a smart meter, suppliers may bill on estimates if data flow fails. If you can show you flagged the problem and tried to provide reads, it can support your position.

6) Exit fees and switching timing

If you’re on a fixed tariff, there may be exit fees. Switching doesn’t remove liability for legitimate debt, but it can stop the problem continuing once you have accurate opening/closing reads.

1) Does the 12-month rule mean my bill is capped at 12 months?

Not exactly. It can mean you shouldn’t be charged for energy used more than 12 months ago where the supplier failed to bill you accurately and you didn’t prevent them from doing so. You can still be billed for the most recent 12 months of usage.

2) Can I get a refund if I’ve already paid a back bill?

Possibly. If the supplier accepts (or is required to apply) back-billing limits and you’ve paid amounts that relate to the period that should be written off, you can ask for a refund or account credit. How it’s paid back can depend on whether your account is open or closed.

3) What if I was billed on estimates for years?

Estimated bills aren’t automatically a back-billing breach, but if the supplier failed to take reasonable steps to bill you accurately (especially if you provided readings), you may have a strong case to limit older charges. Ask for a detailed breakdown and the dates of any actual readings used.

4) I have a prepayment meter — does back-billing apply?

It can. However, outcomes can look different: instead of a big catch-up bill, there may be debt recovery settings or account adjustments. If you’re told you owe money for older periods, ask how it was calculated and whether back-billing limits have been considered.

5) What counts as “not my fault”?

Typical examples include supplier admin errors, wrong meter details, delays after a move-in, or failure to act on readings you submitted. If the supplier argues an exception, ask them to evidence missed appointments, refused access, or ignored requests for information.

6) Should I stop my Direct Debit while I dispute?

Often it’s better to speak to the supplier first. Stopping payments can create arrears and make account handling harder. If you believe amounts are wrong, ask for the account to be put on hold during investigation and agree an interim payment if needed. If you’re in financial difficulty, ask about support options.

7) Can I switch supplier if there’s a disputed balance?

Usually yes, but there are exceptions (for example, if you owe a debt and are on a prepayment meter, or if there’s an active debt transfer). Switching doesn’t remove liability for genuine charges, but it can prevent ongoing billing problems once accurate readings are in place.

8) How long do I have to complain?

Raise the issue as soon as you spot it. Suppliers have complaint procedures, and if it isn’t resolved you may be able to escalate to the Energy Ombudsman after the supplier has had time to respond or if you receive a deadlock letter. Keep everything in writing where possible.

Editorial ownership

Written by

EnergyPlus Editorial Team

Reviewed by

Energy Specialist

Last updated

April 2026

How we assess this topic (and limitations)

• Rule interpretation: We summarise Ofgem guidance and common supplier complaint handling practices for domestic customers in Great Britain.
• Assumptions used in examples: Scenarios use round numbers and assume the supplier’s failure to bill accurately is the main cause of the delay; real bills may involve multiple tariffs, standing charges, price cap periods, or meter exchanges.
• What we don’t do: We can’t determine liability for your exact account or guarantee outcomes. Suppliers may dispute whether an exception applies, and the resolution may depend on evidence, complaint timelines, and the Energy Ombudsman’s view.
• UK scope note: Energy regulation and complaint routes can differ across the UK; the sources below focus on the national regulator (Ofgem) and UK-wide advice bodies.