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

Ofgem’s back-billing rules (often called the 12-month rule) generally mean your energy supplier should not send you a bill for gas or electricity used more than 12 months ago if the lack of correct billing was the supplier’s fault (for example, they failed to bill you or used the wrong meter details). If the rule applies, the supplier should write off charges for energy used over 12 months before the date they issued a correct bill.

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

The 12-month back-billing rule may apply if you were not correctly billed for your energy and it wasn’t your fault. Common examples include: you did not receive bills at all, you were billed to the wrong address, the supplier had incorrect meter details, or they failed to act on information you provided. If the supplier later issues a catch-up bill, they should only charge for energy used in the most recent 12 months (subject to the scheme rules and your circumstances).

When can a supplier bill you for more than 12 months?

A supplier may be able to back-bill beyond 12 months if you prevented accurate billing or did not engage, for example by blocking meter readings, ignoring requests to provide readings, tampering with a meter, or knowingly avoiding payment. Each case depends on the evidence and the applicable back-billing code for your meter type and payment method.

Does the back-billing rule apply to prepayment meters?

Back-billing protections can still be relevant for prepayment customers in situations such as incorrect meter configuration, wrong tariff setup, debt loaded in error, or account/meter registration issues. If you think you’ve been charged incorrectly, raise it with your supplier and ask them to review under the back-billing rules and correct any errors.

How far back can an energy supplier backdate a bill in the UK?

If the back-billing rule applies, suppliers should not charge you for energy used more than 12 months before they issued a correct bill. If it does not apply (for example, due to customer obstruction), a supplier may seek older charges, though you can still challenge accuracy, metering, tariff, and evidence.

Can I get a refund for energy overcharged due to back billing or incorrect billing?

If you’ve been overcharged (for example, billed on the wrong tariff, wrong meter details, incorrect readings, or duplicate charges), you can request a bill recalculation and a refund or account credit. Ask your supplier for a breakdown showing the period billed, readings used, tariff rates, and any adjustments.

What evidence should I gather to challenge a back-bill or request an energy refund?

Useful evidence includes: photos of meter readings and the meter serial number, copies of bills and statements, emails/letters showing you tried to contact the supplier, notes of phone calls (dates/times), proof of moving-in date (tenancy agreement/completion statement), and any historic readings you submitted. This helps show whether the billing failure was the supplier’s fault and supports any refund request.

How do I complain about an energy supplier back-bill in the UK?

Start by contacting your supplier and asking them to apply Ofgem’s back-billing rules and to explain the bill calculation in writing. If the issue isn’t resolved, make a formal complaint through the supplier’s complaints process. If it remains unresolved (typically after 8 weeks) or you receive a deadlock letter, you may be able to escalate to the Energy Ombudsman.

What should I ask my supplier to do to fix the problem quickly?

Ask for: (1) confirmation of your meter serial number and MPAN/MPRN, (2) a full billing breakdown with opening/closing readings and dates, (3) confirmation that the 12-month back-billing rule has been considered, (4) correction of any account/meter registration issues, and (5) a clear outcome—written-off charges (if applicable), a revised bill, and any refund or credit due.

Can EnergyPlus help me understand whether the 12-month rule applies to my situation?

Yes. If you share the dates, billing history, meter details, and any communications you’ve had with your supplier, EnergyPlus can help you understand how the Ofgem back-billing rules may apply, what to request from your supplier, and the practical steps to take to resolve the issue.

Ofgem back-billing rules: 12-month energy refund guide (UK)

Been hit with a catch-up gas or electricity bill for old usage? Learn how Ofgem’s 12-month back-billing rules work, when you may not have to pay, and how to switch to a better tariff with our whole-of-market comparison.

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Understand exceptions (and what evidence to keep)
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Home energy only. We’re a whole-of-market comparison service. Switching won’t affect your complaint rights about back-billing.

What are Ofgem back-billing rules in the UK?

Ofgem’s back-billing rules (often called the 12-month rule) protect domestic customers from being billed for gas or electricity used more than 12 months ago in certain circumstances. If your supplier failed to bill you correctly and then sends a large catch-up bill, you may not have to pay the part that relates to energy used over 12 months before the bill was issued.

This matters if you’ve had an estimated bill for months, no bills at all, a faulty meter situation, or you’ve moved into a property and later receive a surprise charge. The rules are designed to encourage suppliers to bill accurately and in a timely way.

Key point

If you’re covered by the 12-month back-billing rule, you may still need to pay for energy used in the most recent 12 months — but not older usage that should have been billed sooner.

At-a-glance: what to do today

Find the date your supplier issued the back-bill
Identify what part of the bill is for usage over 12 months old
Gather meter readings, emails, move-in date, and account notes
Raise a written dispute and ask for the bill to be reworked under back-billing rules
While you’re at it, compare whole-of-market energy deals

Quick check: could you be protected by the 12-month rule?

Use this checklist as a practical guide before you contact your supplier. If you tick the first two points and nothing in the exceptions section applies, you may have a strong case.

Likely covered

You’re a domestic customer (home energy)
You’re being billed now for energy used more than 12 months ago
You tried to provide meter readings or access and were ignored
Your supplier failed to bill you (or billed incorrectly) due to their error
There’s been a billing delay after a meter exchange or account setup issue

May not be covered

You stopped the supplier reading the meter (no access) repeatedly
You tampered with the meter or there’s energy theft investigation
You ignored requests for information needed to bill you
The bill relates to a period where you had a prepayment meter and charges were collected as you used energy
You’re being billed for the last 12 months only (the rule doesn’t remove recent charges)

Important: This guide is for information. Your supplier must follow licence conditions and industry rules, but outcomes depend on your exact billing history and evidence. If you’re struggling to pay any bill, ask about a payment plan and support options while your dispute is considered.

Compare whole-of-market energy tariffs (and reduce future billing shocks)

A back-bill dispute can take time. In the meantime, switching to a better-value tariff could reduce your monthly costs and help you regain control. EnergyPlus compares whole-of-market home energy deals, so you can see options beyond a single provider.

What you’ll need (2 minutes)

Your postcode (to find available tariffs)
Rough usage (or your latest bill if you have it)
Whether you have a smart meter (if known)
Your contact details so we can share results and next steps

Switching supplier doesn’t remove your right to challenge incorrect historic bills. Keep copies of all emails, bills, and meter readings.

Get whole-of-market results

Why compare while dealing with a back-bill?

Because a dispute is about historic billing, but your household budget is about today’s unit rates and standing charges. If your current tariff is uncompetitive, switching could help offset higher costs and reduce the chance of payment difficulty in future.

Why the 12-month back-billing rule helps consumers

Protects you from supplier delays

If billing errors are on the supplier’s side, the rules can prevent large unexpected charges for older periods that you couldn’t reasonably plan for.

Encourages accurate meter reading

Suppliers should take regular reads (or accept yours) and keep accounts up to date. Long runs of estimates can create big corrections.

Supports fair complaint outcomes

Where you’ve acted reasonably, the rule helps ensure you’re not penalised for problems you didn’t cause, especially after moving home or changing supplier.

How to challenge an energy back-bill (step-by-step)

If you think your supplier has billed you for energy used more than 12 months ago, take these steps. Keep everything in writing where possible (email or online account messages) so there’s a clear audit trail.

Identify the billed period: Note the start and end dates on the catch-up bill and the date it was issued.
Split the charges: Work out what usage falls within the last 12 months and what falls outside it.
Gather evidence: Save meter readings, photos, move-in confirmation, tenancy agreement, and any communications showing you tried to resolve billing earlier.
Write to your supplier: Ask them to apply Ofgem back-billing rules and reissue a corrected statement. Request a written explanation if they refuse.
Ask for a hold on collections: If the bill is disputed, ask them to pause debt collection activity while they investigate (keep paying what you genuinely owe if you can).
Escalate if needed: Follow the supplier’s complaints process. If unresolved after the appropriate process/time, you may be able to take it to the Energy Ombudsman.

Template wording you can adapt

"I’m disputing this bill as it includes charges for energy consumed more than 12 months before the bill was issued. Please review my account and apply the Ofgem back-billing rules. I request a revised bill excluding any amounts older than 12 months, along with a written explanation of how you’ve calculated the remaining balance."

Examples: when the 12-month back-billing rule may apply

These scenarios help you map the rule to real household situations. Always check dates carefully: the 12 months is typically measured back from the date the supplier issues a bill that first includes the previously unbilled consumption.

Situation	What happened	Likely outcome
No bills for 18 months	Supplier failed to set up billing after move-in despite you contacting them	You may not have to pay for usage older than 12 months
Long run of estimated bills	Supplier ignored your reads then “reconciled” two years of usage	Older portion may be removed if the failure to bill accurately is the supplier’s fault
Meter exchange delay	After a new meter, the account wasn’t updated and charges were missed	Back-billing protection may apply depending on who caused the delay
You blocked meter access	Supplier repeatedly asked for access or readings and you didn’t respond	Protection may not apply; supplier may bill beyond 12 months in some cases

Exceptions: when a supplier might still bill beyond 12 months

The back-billing rule is a strong consumer protection, but it isn’t a blanket waiver. Suppliers may argue the rule doesn’t apply if the customer’s actions prevented accurate billing.

No reasonable access to read the meter over a long period (where access was requested)
Failure to provide information needed to set up or maintain the account when requested
Meter tampering or suspected energy theft
Supplier billed correctly but you didn’t pay (this is different from back-billing)

Evidence to strengthen your position

Dated meter photos showing readings you submitted
Emails or screenshots of online submissions
Call logs (date/time) and complaint references
Move-in/out documents and tenancy agreements
Any supplier messages acknowledging billing delays

Tip: If you have a smart meter, ask the supplier to confirm whether the meter was communicating during the disputed period. Communication issues can contribute to long estimates.

Common back-billing mistakes to avoid

Assuming the full bill is wiped

Even if protected, you may still owe for the most recent 12 months. Ask for a revised statement that separates older and recent charges.

Not disputing in writing

Phone calls can be missed or misunderstood. Send a clear written request and keep copies so dates and wording are recorded.

Forgetting your move dates

Back-bills can include periods before you moved in. Ensure the supplier bills the correct occupier and uses accurate opening/closing reads.

FAQs: Ofgem back-billing rules & 12-month energy refund

Do I get a refund or do I just not have to pay?

Often it’s a revised bill removing older charges, rather than money paid back. If you’ve already paid amounts that should not have been billed under the 12-month rule, ask your supplier to confirm whether a credit/refund is due.

Does the rule apply if I moved home?

It can. Disputes often involve incorrect move-in dates or missing opening readings. Provide proof of occupancy dates and ask the supplier to correct the account and apply back-billing rules where relevant.

What if my bills were estimated?

Estimated bills aren’t automatically unfair, but long periods of estimates followed by a large catch-up can trigger back-billing protection if the supplier failed to take reads or ignored readings you supplied.

Should I stop paying while I complain?

If you can, keep paying what you believe is accurate for the last 12 months and request the supplier places disputed amounts on hold. If you’re struggling, ask for a payment plan and support options.

Does switching supplier affect my back-bill dispute?

Switching doesn’t remove your right to dispute incorrect billing for a past period. Keep all documents and continue the complaints process with the supplier who issued the bill.

Is the 12-month rule the same across Great Britain and Northern Ireland?

Energy regulation differs across the UK. This page is UK-focused for domestic customers; if you’re in Northern Ireland, check your supplier’s terms and the relevant local regulatory guidance as processes can vary.

If you’re in immediate financial difficulty: Tell your supplier and ask about hardship support, emergency credit (if prepay), and a manageable repayment plan. You can do this alongside a back-billing dispute.

Trusted, whole-of-market comparison

Clear next steps

We keep the process simple: share your postcode and details, then we’ll help you understand available home energy options and what to do next.

Whole-of-market options

Compare across the market so you’re not limited to one supplier’s prices. Focus on value: unit rates, standing charges, and tariff type.

Customer-first guidance

Back-billing questions can be stressful. This guide explains the rule in plain UK English and helps you organise evidence before you contact your supplier.

Want to reduce the chance of future billing problems? Submit regular meter readings (or confirm your smart meter is communicating), keep move-in/out photos, and review your tariff at least once a year.

Ready to cut your energy costs?

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Back-bill checklist (save this)

Keep dated meter photos
Request a revised bill splitting older vs recent usage
Ask for disputed sums to be placed on hold
Follow complaints process and escalate if needed

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Updated on 3 Feb 2026