What are Ofgem’s back-billing rules (the 12-month rule)?

Ofgem’s back-billing rules (often called the 12-month rule) generally mean your energy supplier should not send you a new bill for energy used more than 12 months ago if you have not been correctly billed and the issue was not your fault. If you have been underbilled due to supplier error, the supplier is usually limited to charging for the most recent 12 months only.

When does the 12-month back-billing limit apply?

The limit can apply when you have not received an accurate bill for more than 12 months due to supplier issues (for example, billing delays, incorrect meter details, or account errors) and you have not prevented billing. In these circumstances, charges for energy used more than 12 months earlier are typically not recoverable under the back-billing rules.

When might the back-billing rules not protect me?

You may not be protected if you have behaved unreasonably or prevented accurate billing—for example by repeatedly refusing meter access when required, knowingly giving incorrect information, or ignoring requests needed to set up correct billing. If you are unsure, gather your account history and communications and ask your supplier to explain why the rule does or does not apply.

Does the back-billing rule apply to smart meters and prepayment meters?

Back-billing protections can still be relevant with smart meters (including when reads or billing data fail) and in some cases for prepayment customers. Your supplier should review the circumstances and explain how the rules apply to your account, particularly if you have not received accurate bills or statements for an extended period.

What should I do if I receive a large ‘catch-up’ energy bill?

First, check the bill dates and what period it covers. Ask your supplier for a full breakdown (reads used, tariff, and account changes) and confirm whether Ofgem’s 12-month back-billing rules apply. If the bill includes charges older than 12 months due to supplier error, request that those charges are removed. If you still need help, raise a formal complaint and keep all evidence (bills, emails, and meter readings).

Can I get a refund if I have been overcharged?

If you have been overcharged, you can ask your supplier to correct your account and issue a refund or credit. Provide supporting evidence such as meter readings and copies of bills. If the supplier agrees there has been an error, they should explain the correction and how and when you will receive the refund or account credit.

How do I complain to my energy supplier about back-billing or refunds?

Start by contacting your supplier and clearly state that your complaint relates to back-billing and/or an energy refund. Request a written response with a timeline for resolution. If the issue is not resolved, escalate through the supplier’s complaints process. If you reach deadlock or it has been eight weeks, you may be able to take the case to the Energy Ombudsman.

How can EnergyPlus help if I’m confused about my billing history?

EnergyPlus shares guidance and updates on UK energy rules and billing issues, including back-billing and refunds. If you are reviewing your options, you can also compare energy deals and consider switching to a tariff that better fits your usage. Visit https://www.energyplus.co.uk/ to explore guidance and tools.

Ofgem back-billing rules: claim up to 12 months energy refund

If your supplier has billed you late or not billed you at all, Ofgem’s back-billing rules may mean you don’t have to pay for energy used more than 12 months ago. Understand your rights, check if you qualify, and compare whole-of-market tariffs to avoid future bill shocks.

Learn when the 12-month back-billing limit applies (and when it doesn’t)
See what evidence to gather before you contact your supplier
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Check my options & compare Am I protected by the 12-month rule?

EnergyPlus is a UK comparison service for home energy (whole-of-market). We’ll show available tariffs; your supplier remains responsible for billing and back-billing decisions.

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Back-billing issues often happen when there are missed meter reads, account set-up problems, or incorrect meter details. Switching to a tariff that suits your usage — and keeping your account details accurate — can reduce the risk of sudden catch-up bills.

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Important: This page provides general information for UK households. It isn’t legal advice. Ofgem rules can change, and outcomes depend on your circumstances.

What are Ofgem back-billing rules?

Back-billing is when your energy supplier tries to charge you now for energy you used in the past because you weren’t billed correctly at the time. Ofgem introduced back-billing rules so households are protected from paying for energy used more than 12 months ago when the supplier is at fault for the billing delay.

What the 12-month limit means in practice

If a supplier failed to bill you, they generally can’t charge for energy used over 12 months before they corrected the issue.
This can apply to gas and electricity, including where estimated bills were wildly wrong and the supplier didn’t take reasonable steps to fix it.
You may see the older charges removed, a rebill, or an account credit/refund depending on what you’ve already paid.

Why it happens

Incorrect meter details (serial number/MPAN/MPRN mismatch)
Change of tenancy or move-in not processed properly
Supplier didn’t act on meter reads (manual or smart)
Billing system errors after switching supplier
Meter exchange not updated on the account

If you think you’re facing a catch-up bill for older usage, jump to eligibility and exceptions then follow the step-by-step claim process.

Am I covered by the 12-month back-billing rule?

You’re more likely to be protected if the supplier caused the delay and you have acted reasonably (for example, you didn’t block access to a meter and you provided readings when asked). The key question is whether you could reasonably have known you were being under-billed or not billed.

Likely covered

No bill (or clearly wrong bills) for months
You tried to contact the supplier and keep records
Supplier ignored reads or didn’t correct known errors
Account set-up issue after switch/move-in

May be excluded

You stopped the supplier getting reads (where required)
You didn’t pay despite having accurate bills
You intentionally avoided contact or provided misleading info
The issue relates to theft or tampering

What to check first

Date the supplier first issued a correct bill/rebill
What period the bill covers (start/end dates)
Whether reads were estimated or actual
Your contact history (emails, calls, complaints)

Quick self-check: If your supplier is charging today for usage that ended more than 12 months ago and the delay wasn’t your fault, ask them to apply the back-billing rules and remove the older portion.

How to claim: 7 steps to challenge a late energy bill

Use this process to request a back-billing adjustment, credit, or refund. Keep everything in writing where possible.

Get a full bill breakdown showing the exact dates being charged, meter readings used (actual/estimated), and tariff rates.
Identify the “older-than-12-months” period. Mark any days/months that ended more than 12 months before the corrected bill date.
Gather evidence: photos of meter reads, move-in date, tenancy agreement, emails/call logs, and any previous bills.
Contact the supplier and reference back-billing. Ask them to remove charges older than 12 months where the delay is their fault.
Request a corrected statement (rebill) and confirm how any overpayment will be returned (refund vs. account credit).
Raise a formal complaint if they refuse or delay. Ask for a deadlock letter if they won’t resolve it.
Escalate if needed to the Energy Ombudsman after the supplier’s process (or after the relevant time period), providing your evidence pack.

Template wording you can use

Copy/paste into an email or online chat:

I’m disputing the charges on my bill dated [DATE] for the period [START–END]. Please apply Ofgem’s back-billing rules and remove any charges for energy used more than 12 months before the date the bill was corrected, where the delay was not my fault. Please provide a rebill with the revised dates/reads and confirm whether any overpayment will be refunded or credited.

What to ask for (checklist)

Rebill removing older-than-12-month charges (if applicable)
Written explanation of why they think any exception applies
Confirmation of meter serial number and meter type
Confirmation of MPAN (electric) / MPRN (gas) on the account
A repayment plan for any remaining balance you do owe

Back-billing examples (UK households)

These scenarios show how the 12-month rule can affect what you pay. Your supplier should be able to show the calculation on a revised statement.

Situation	What happened	How the 12-month rule may help
No bills after moving in	Supplier didn’t set up the account correctly for 18 months.	Charges for the first 6+ months may be removed if the delay wasn’t your fault.
Estimated reads far too low	You paid monthly but supplier didn’t correct estimates despite usage evidence.	Older underbilled consumption may be capped at 12 months if supplier failed to act.
Meter exchange not updated	New meter installed; readings weren’t captured, leading to a later catch-up.	If the supplier’s admin caused the delay, older charges may be removed.
Supplier says an exception applies	They claim you prevented access or ignored requests for reads.	Ask for evidence (dates, letters, attempts). If wrong, escalate via complaints/ombudsman.

Keep it simple: You’re not asking for “free energy”. You’re asking the supplier to follow the rule that prevents them billing you late for older consumption when the delay wasn’t your fault.

Common mistakes that weaken a back-billing claim

Not dating the 12-month window

Suppliers may issue a rebill that still includes older usage. Always compare the bill date and the usage period end date.

No evidence pack

Screenshots, emails, meter photos, and move-in dates help show you acted reasonably and the delay wasn’t your fault.

Ignoring the “what you do owe” part

The rule may remove older charges, but you may still owe for the most recent 12 months. Ask for an affordable repayment plan if needed.

FAQs: Ofgem 12-month back-billing (UK)

Does the back-billing rule mean I get a 12-month energy refund?

Not always. The rule usually means your supplier can’t bill you for energy used more than 12 months ago if the lack of billing was their fault. If you’ve already paid for those older charges, you may be due a refund or account credit. If you haven’t paid yet, it may simply reduce what you owe.

Does it apply to smart meters?

It can. Even with smart meters, billing can go wrong (for example, data not received, account issues, or incorrect meter registration). Ask the supplier for the reads they used and when they became aware of the issue.

What if I gave meter readings but they still estimated?

Tell the supplier exactly when you submitted readings (include screenshots/emails). If they didn’t use them or didn’t investigate obvious problems, that can support your request to apply the 12-month back-billing limit.

Can my supplier back-bill me for more than 12 months if I didn’t pay?

If you received accurate bills and didn’t pay, that’s different from a supplier failing to bill you. Back-billing protections are aimed at late billing caused by the supplier. If you’re struggling, ask for a repayment plan and check if you qualify for support.

What if I’m on a prepayment meter?

Back-billing issues can still happen (for example, incorrect meter setup or debt recovery problems). Request a statement of account and ask them to explain how any shortfall was calculated.

Will switching supplier affect my back-billing complaint?

You can still pursue a complaint about past billing. However, switching may be affected if there’s an outstanding balance or an active dispute. If you want to switch, get everything in writing and keep copies of meter reads on the day you switch.

Want to reduce the chance of billing problems going forward? Compare whole-of-market tariffs and keep your meter reads up to date.

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“We had a surprise catch-up bill after months of estimates. The steps here helped us ask the right questions, and we switched to a tariff that matches our usage.”

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Updated on 25 Dec 2025