Energy Firms Wrote Off £172m Under Backbilling Rules: Ofgem

What Ofgem examined and why

Billing is the single biggest source of friction between energy suppliers and their customers, accounting for around 30% of complaints to suppliers and 55% of cases referred to the Energy Ombudsman, and Ofgem's Domestic Billing Performance Assessment, published on 27 July, is the regulator's attempt to understand why. The review covered the seven largest credit meter suppliers, British Gas, EDF, E.ON Next, Octopus Energy, OVO, Scottish Power and Utility Warehouse, each with at least a million credit meter customers, examining billing accuracy, timeliness, backbilling protections and the meter reading services offered to vulnerable customers. The headline picture is better than the complaint volumes suggest: 99% of customers receive the required number of bills each year, 81% of bills are based on actual meter readings at first issue rising to 89% after reconciliation, and satisfaction with bill accuracy runs at 77%. Ofgem's explanation for the gap is that billing is where every other problem surfaces: affordability, meter faults, tenancy changes and the sheer cost of energy all arrive in a customer's life as a bill, and with over 300 million bills issued in 2024, even a small failure rate lands on millions of households. The assessment feeds Ofgem's shift to outcomes-based regulation, which begins with the billing rules.

Backbilling: the 12-month rule and £172m written off

The strongest consumer protection in the report is also the least understood. Backbilling rules prevent suppliers from recovering charges for energy used more than 12 months ago where the supplier was at fault for not billing it, for example where an account went unbilled or readings were ignored. The assessment shows the rule has real teeth: the seven suppliers wrote off charges for almost 1 million customers, totalling over £172 million, just under £200 per affected customer. The gaps sit in the detail. Average resolution times for backbilling cases range from around 2 months at the best suppliers to almost 10 at the slowest, and even a correctly applied rule leaves customers facing a catch-up bill covering up to 12 months of genuine usage, which can run to four figures for a household that assumed a silent supplier meant nothing owed. Ofgem also found weaknesses in how suppliers record their use of backbilling exceptions, the narrow circumstances such as energy theft or deliberately blocking meter access in which the protection does not apply, and signalled possible further guidance to keep exceptions narrow. Any customer hit with charges older than 12 months should cite the backbilling rules to their supplier directly, and escalate to the Energy Ombudsman if refused, where backbilling already accounts for around 5% of referrals.

Late bills and the shock factor

Timeliness is where the assessment found the clearest underperformance. While 97% of bills arrived within 30 days of being due, around 11 million bills in 2024, roughly 3% of the total, were issued at least a month late, and 3.5 million of those arrived between three and twelve months late. Late billing is the raw material of bill shock: a household paying on receipt of bills rather than by fixed direct debit can accumulate months of unbilled usage and then face it all at once, precisely the situation the backbilling rules exist to cap at the 12-month mark. Ofgem found the late bills concentrated among a smaller cohort of suppliers and generally driven by system migrations and operational problems rather than sector-wide failure, and says it is working directly with those suppliers on improvement plans it expects to deliver significant reductions. For customers, the defensive moves are unglamorous but effective: check that bills are actually arriving on schedule rather than assuming silence is good news, submit meter readings regularly if you do not have a working smart meter, since estimated bills are where errors compound, and query a missing bill with the supplier in writing, which both prompts the bill and creates the paper trail that matters if the account later turns into a backbilling dispute.

The free service 8 million people are not using

The report's quietest finding may be its most useful. Around 9 million customers, a quarter of the market, are registered on the Priority Services Register, the free scheme for people who are older, disabled, chronically ill or otherwise in a vulnerable situation, but only around 1 million are registered for its free meter reading service, under which the supplier must read the meter for customers who cannot do so themselves. Ofgem found significant variation in how suppliers deliver the service and in how they identify who needs it, with some enrolling eligible customers automatically and others waiting to be asked, and is pushing several suppliers to improve the success rate of reading visits. Anyone who struggles to read their meter, or has a household member who does, should ask their supplier to join the PSR and specifically request the meter reading service, both free. The register also brings advance notice of planned power cuts, accessible bill formats and password schemes for doorstep callers. The other structural fix is the one Ofgem repeats throughout: customers with working smart meters get the most accurate bills with the fewest estimates, and requesting one costs nothing. The full assessment is on Ofgem's website, linked in the sources below. Related: our money guides, bills section, comparison guides and the latest UK news.

Frequently asked questions

What is the energy backbilling rule?

Suppliers cannot recover charges for energy used more than 12 months ago where they were at fault for not billing it. Ofgem's assessment found over £172 million written off for almost 1 million customers under the rule.

What should I do if my supplier sends a bill for old energy use?

Check the dates. If any charges cover usage more than 12 months old and the supplier failed to bill you, cite the backbilling rules and ask for those charges to be removed. Escalate to the Energy Ombudsman if refused.

How many energy bills arrive late?

Around 11 million bills, 3% of the 309 million issued in 2024, were at least a month late, with 3.5 million between three and twelve months late. Ofgem found late bills concentrated at a small group of suppliers.

What is the Priority Services Register meter reading service?

A free service for PSR customers who cannot read their own meter, under which the supplier must read it for them. Around 9 million people are on the PSR but only about 1 million use the meter reading service.

Do smart meters make bills more accurate?

Yes. Ofgem found customers with working smart meters experience higher billing accuracy and fewer estimated bills, and expanding smart meter coverage is its main route to better billing outcomes.