Back-Billing Rules for Energy Explained

Back-billing rules for energy stop your supplier charging you for gas or electricity you used more than 12 months ago, where you were not correctly billed for it before. This is an Ofgem licence obligation that protects UK households from sudden, large catch-up bills caused by the supplier’s own mistakes. It applies to all domestic customers in Great Britain, whatever your meter or payment type.

If a supplier failed to send accurate bills and then tried to charge you for years of usage, the back-billing rule limits what you owe. It does not, however, wipe out energy you were already correctly billed for and simply did not pay.

• Ofgem’s 12-month back-billing rule means you cannot be charged for unbilled energy used more than 12 months ago, if the delay was the supplier’s fault.
• It covers gas, electricity and standing charges, across direct debit, prepayment and standard credit accounts.
• It does not apply if you obstructed billing, for example by blocking meter access or tampering with the meter.
• It is not the same as energy debt: bills you received correctly but did not pay can still be chased for up to six years.

What the Ofgem 12-month back-billing rule actually covers

The Ofgem 12-month back-billing rule means a domestic energy supplier cannot bill you for gas or electricity used more than 12 months ago if you were not properly billed for it at the time. Ofgem introduced this as a licence condition banning suppliers from issuing back bills beyond 12 months, after research found typical catch-up bills of around £1,160 and extreme cases running into thousands of pounds.

The protection covers unbilled usage and standing charges. According to Ofgem’s consumer guidance (live as of 23/06/2026), you cannot be charged for energy used more than 12 months ago if you have not had an accurate bill for it before, even though you asked for one, or you were never told about the charges through a statement of account.

The rule applies to all payment methods and meter arrangements: monthly direct debit, standard credit, prepayment, smart and traditional meters. It protects households, not businesses. Microbusinesses have their own version of the rule, but commercial and non-domestic energy contracts are outside the scope of this guide.

When you don’t have to pay a back bill

You do not have to pay for energy used more than 12 months ago when the failure to bill you accurately was the supplier’s fault. Ofgem and Citizens Advice set out several situations that fall under the back-billing principle.

• Your supplier never billed you at all, even though you asked for bills.
• You were billed on estimated readings instead of the valid readings you provided.
• Your bills were wrong because the supplier mixed up meter readings or ignored information it held.
• The supplier failed to act on a query or fault and let a large debt build up.
• Your direct debit was set too low to cover your actual usage and was not reassessed within around 15 months.

In any of these cases, the supplier can only charge you for the most recent 12 months of unbilled energy. If they already took money for the older period, they should refund all or part of it.

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Back-billing versus energy debt: the difference that catches people out

Back-billing is being charged late for energy you were never properly billed for in the first place, while energy debt is being billed correctly and then not paying. This distinction is the single biggest source of confusion, and it decides whether the 12-month protection helps you.

If you received an accurate, estimated or final bill and simply did not pay it, that is debt, not back-billing. A supplier can pursue a properly issued unpaid bill for up to six years under standard limitation rules. The 12-month rule does not erase money you owe on bills you already received.

The protection also does not write off your first 12 months. If a supplier sends you a single correct bill covering a longer period that it failed to bill earlier, the rule limits the charge to the most recent 12 months of that gap, not to nothing at all.

Does the rule apply if you have a smart meter?

The back-billing rule applies regardless of whether you have a smart meter, but the cause of a back bill is different with smart metering. Ofgem’s view, expressed by its director Tim Jarvis in 2025, is that where a supplier receives accurate and timely readings through a working smart meter, there is no reasonable cause for back-billing at all.

Problems still arise when a smart meter loses its connection and stops sending readings, or reverts to estimated billing. Around 3.2 million smart meters in Great Britain are not operating in smart mode, according to figures Ofgem cited in 2025. If yours sends estimates while you provided accurate readings, the back-billing protection can still apply.

If your provider has raised your monthly amount despite accurate readings, our guide on a direct debit increased while in credit explains your options.

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What counts as ‘unreasonable’ behaviour that removes protection

The back-billing rule does not protect you if you actively prevented your supplier from billing accurately, for example by tampering with a meter, stealing energy, or blocking access for meter readings. Ofgem describes this as obstructive or manifestly unreasonable behaviour.

Importantly, simply failing to send meter readings is not classed as unreasonable. Ofgem has confirmed consumers are not at fault for not providing readings, because suppliers have other ways to obtain accurate data. The exemption is meant for genuine obstruction, not for ordinary customers who never got round to submitting a reading.

This is a recognised grey area. The rule is principles-based rather than listing exact examples, so what counts as “unreasonable” is judged case by case. If a supplier claims you obstructed billing, ask them to explain precisely what you did to prevent accurate billing, and keep your own record of readings you submitted and access you allowed.

Can you be back-billed for a property you’ve moved out of?

Yes, the 12-month back-billing rule still applies to a former property, so a supplier cannot charge you for energy used there more than 12 months ago if you were not correctly billed at the time. Households sometimes receive a catch-up bill, or even a refund, for a previous home long after moving.

If a final bill for an old address arrives late and covers a long unbilled period, you are only liable for the most recent 12 months of that usage, assuming you did not obstruct billing. Always give your closing meter readings on the day you move and keep a dated photo, because that protects you if the figures are later disputed.

How to dispute a back bill with your supplier

To dispute a back bill, write to your supplier stating that you are protected by Ofgem’s back-billing rules and should only be charged for the most recent 12 months of energy use. Put it in writing, keep a copy, and reference the specific period you are disputing.

Citizens Advice publishes a free back-billing example letter you can adapt, and its consumer helpline can talk you through it. If money was already taken for the older period in error, the supplier should refund all or part of the bill once the rule is applied.

Follow these steps if you receive an unexpected catch-up bill:

• Check whether you were ever sent an accurate bill or statement for the period in question.
• Confirm whether you submitted readings or allowed meter access during that time.
• Write to the supplier quoting the back-billing rules and the dates involved.
• Ask for a corrected bill limited to the last 12 months and a refund of any overcharge.
• Request a payment plan if you still owe for the past 12 months.

You are entitled to a fair payment arrangement for any back bill you do owe. Suppliers generally spread repayment over a period similar to the one the debt built up over, so a six-month back bill should usually give you around six months to clear it.

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Escalating to the Energy Ombudsman

If your supplier does not resolve a back-billing complaint within eight weeks, or sends a deadlock letter, you can take it to the Energy Ombudsman for a free, independent review. The Ombudsman can order the supplier to correct the bill, refund overcharges and sometimes pay compensation.

Back-billing makes up only around 4 to 5% of complaints reaching the Energy Ombudsman, according to Energy UK, but the cases that do reach it can involve large sums. Keep all correspondence, readings and dates, as the Ombudsman will weigh up whether the supplier billed you correctly and whether you obstructed billing.

It is also worth knowing your wider Ofgem rights when switching energy suppliers, since billing disputes sometimes surface when you change tariff or move home.

Why back bills happen and the push to tighten the rules

Back bills usually happen because a supplier billed on estimates, missed a meter fault, set a direct debit too low, or carried over readings incorrectly. With energy unit rates higher than they were a few years ago, an under-billed account can build a sizeable shortfall before anyone notices.

The Ofgem energy price cap from 1 July to 30 September 2026 is expected to set a typical annual bill of around £1,663 based on currently published figures, after Ofgem updated its typical usage assumptions. The cap limits unit rates and the standing charge for a typical household, not a fixed total bill, so the more energy you use the more an unbilled period can add up.

There is active pressure to shorten the back-billing window. In March 2025, consumer campaigners and MPs argued the period should be cut from 12 months to six, and that back bills should carry a clear warning telling customers their rights. Ofgem has acknowledged that, with accurate smart meter data, there is little justification for back-billing at all. The 12-month rule remains in force as of 23/06/2026, but the direction of travel is towards stronger protection.

For context on how supplier conduct is policed, see our coverage of how a supplier was fined for breaking the rules.

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Information correct as of 23 June 2026. Prices, tariffs, policy details and providers change frequently, so please check the latest details before making a decision. This article is for general information only and does not constitute financial advice.