Energy suppliers wrote off more than £172 million in charges for almost one million households under rules protecting customers from excessively late bills, Ofgem has revealed.
The regulator’s first detailed assessment of domestic billing found most customers receive regular and broadly accurate bills but warned that weak record keeping could lead to backbilling protections being applied inconsistently.
Suppliers are normally prevented from recovering charges for energy used more than 12 months earlier where the delay was their fault. The write-offs averaged just under £200 for each affected customer.
However, Ofgem found large differences in how quickly cases were resolved, with average times ranging from around two months to almost 10 months, depending on the supplier.
Customers can still receive catch-up bills covering up to a year of previous consumption even when the rules are applied correctly.
Backbilling disputes account for around 5% of all cases referred to the Energy Ombudsman.
Ofgem said exceptions should only be used in narrow circumstances, including energy theft or where a customer has deliberately blocked access to a meter.
It found many suppliers had weaknesses in the way they recorded those exceptions, raising the risk that customers could face different outcomes depending on which company supplied their energy.
The assessment covered British Gas, EDF, E.ON Next, Octopus Energy, OVO, ScottishPower and Utility Warehouse, each of which has at least one million credit meter customers.
Ofgem found 81% of bills were based on actual meter readings when first issued, rising to 89% after later reconciliation. Smart meter customers generally received more accurate bills and relied less heavily on estimates.
Around 99% of customers received the required number of bills but timeliness remained a concern.
Suppliers issued approximately 309 million bills during 2024, with 11 million arriving at least one month late. Of those, 3.5 million were between three and 12 months overdue.
Late bills were concentrated among a smaller group of suppliers and were generally linked to system migrations or operational failures.
Billing and meter reading now account for around 30% of supplier complaints and 55% of Energy Ombudsman referrals.
Ofgem said it is working directly with suppliers through targeted improvement plans, stronger oversight and further guidance designed to ensure backbilling protections are applied consistently across the market.
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