Large suppliers: Domestic dual fuel bill breakdown over time


Javascript is required to render chart Large suppliers: Domestic dual fuel bill breakdown over time.

Source: Ofgem analysis of companies’ Consolidated Segmental Statements.

Information correct as of: August 2019

This chart provides an estimate of the breakdown of a dual fuel bill over time for an average domestic customer of the large suppliers.  It is based on information reported by the large suppliers in their annual Consolidated Segmental Statements. For more information, please see our page Understanding the profits of the large energy suppliers. Earnings Before Interest and Tax (EBIT) – which we also refer to as suppliers’ pre-tax margins – are calculated as revenue minus costs, before accounting for taxes and interest.

Policy Areas:

  • Electricity - retail markets
  • Gas - retail markets

Data Table

Large suppliers: Domestic dual fuel bill breakdown over time
Wholesale costsDirect costsNetwork costsEnvironmental/social costsOther direct costsOperating costsEBITVATBill

More information

Domestic dual fuel bill breakdown over time: At-a-glance summary

Between 2009 and 2018, the average domestic dual fuel bill has fluctuated, reaching a peak of £1,286 in 2013. In 2018 it increased to £1,184 from £1,117 in 2017, mainly as a result of an increase in wholesale and environmental/social costs.

The large suppliers’ financial statements have shown a marked difference in outturns for gas and electricity. Despite the fall in revenues, aggregate pre-tax profits from the supply of gas increased year-on-year, while for electricity they fell significantly.

Relevance and further information

This indicator helps to explain the costs making up an average dual fuel bill and show the factors influencing total bills in a given year. The costs that make up a bill are wholesale costs, network costs, environmental and social obligation costs, operating costs (including depreciation and amortisation), supplier pre-tax margin and VAT.


To estimate the breakdown of an average gas and electricity bill, we took the sum of each category of costs and pre-tax supply margins as reported by the suppliers for each fuel and then divided by the total number of customers for that fuel. We then added VAT at 5% and summed the implied bill components for gas and electricity together to derive an estimate of the overall costs making up a dual fuel bill.

Note that because it is based on the total costs and customer numbers reported by suppliers irrespective of their tariff type, the bill breakdown for gas will reflect a mixture of the costs of serving gas to dual fuel and single fuel customers – and the same also applies to electricity. As such, the dual fuel breakdown should be considered an approximation in that it will reflect a combination of the costs incurred in serving gas and electricity to both dual fuel and single fuel customers (which may differ if, for example, electricity-only customers consume more electricity than those customers that are also supplied with gas).

The data presented is based on the latest available Consolidated Segmental Statements. It may differ from the data that can be found in the supplier’s externally published Consolidated Segmental Statements. This is because we have made some adjustments to the way in which exceptional items are reported among suppliers 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.

Date correct
August 2019
Policy areas