Methodology
To estimate the breakdown of an average gas and electricity bill, we:
- Took the sum of each category of cost (e.g. wholesale, network etc) and the pre-tax supply margin reported by the suppliers for gas. Did the same for electricity.
- Divided the gas sum by the total number of customers and added VAT at 5%. Did the same for electricity.
- Added together the resulting two figures to get a combined estimate of the overall cost of a dual fuel bill.
Please note that chart calculations are drawn from suppliers’ reported total costs and total customer numbers, irrespective of tariff type. They will therefore reflect a mixture of the costs to supply dual fuel and single fuel customers. As such, the dual fuel breakdown is an approximation – values may differ, for example, if electricity-only customers use more electricity than those customers who are also supplied with gas.
The data presented is based on the latest available Consolidated Segmental Statements (CSS). It may differ from the data in the suppliers externally published CSS. This is because we have made some adjustments to the way exceptional items are reported to improve comparability.
Figures relate to the suppliers’ financial years. Five of the companies (British Gas, EDF, E.ON, npower and ScottishPower) have financial years ending in December, whereas SSE’s financial year runs from April to March.
Following OVO’s acquisition of SSE’s domestic supply business, the average domestic dual fuel bill for 2020 does not include OVO/SSE’s data. This is because in 2020 OVO did not hold any generation licence and was not legally required to submit a Consolidated Segmental Statement.
