Pre-tax domestic supply margins of large legacy suppliers, combined gas and electricity


Source: Companies’ consolidated segmental statements.

Information correct as of: August 2020

This chart shows the combined gas and electricity pre-tax domestic supply margins of the large legacy suppliers. It is based on information reported by the large legacy suppliers in their annual Consolidated Segmental Statements.

We update this chart on an annual basis. Click the ‘more information’ tab above for a summary of the key figures, details of how to interpret the figures and for information on our methodology.

Policy Areas:

  • Electricity - retail markets
  • Gas - retail markets

Data Table

Pre-tax domestic supply margins of large legacy suppliers, combined gas and electricity
British GasE.ONEDFnpowerScottishPowerSSEAggregate

More information

Pre-tax supply margins of the large legacy suppliers: At-a-glance summary

Between 2009 and 2016, the average combined gas and electricity pre-tax domestic supply margin across the large legacy suppliers grew from around 1% to around 4%, with significant differences between the suppliers’ margins.

Between 2016 and 2019, profits earned by the large legacy suppliers continued to vary substantially, but generally showed a decrease in the average combined gas and electricity pre-tax domestic supply margin, falling to -1.5% in 2019. All large legacy suppliers experienced a reduction relative to 2018 values, leading to a lower variation across suppliers’ margins in 2019 compared to previous years. All suppliers, except for Centrica, made a loss in the domestic supply segment in 2019. EDF and Scottish Power saw the largest decrease in their margins, falling from 1.8% to -6.1% and from 4.2% to -2.1% respectively. E.ON experienced the smallest change, from -0.3% to -1.3%.

In 2020, OVO completed the purchase of SSE and E.ON acquired npower. The Consolidated Segmental Statements of 2019 are not affected by these sale transactions.

Relevance and further information

This chart helps us understand trends in profits in the domestic supply market and how they differ between suppliers.


The supply margins shown in this chart are the ratio between a company’s Earnings Before Interest and Taxes (EBIT) - the ‘pre-tax margin’ - and its total revenues from supplying gas and electricity.

A supplier’s pre-tax margin is calculated by subtracting from a company’s total revenue its total direct costs, total indirect costs (such as operating costs), depreciation and amortisation for supplying energy.

Figures are calculated using information from companies’ annual Consolidated Segmental Statements. They 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. 

The data in this chart may differ from the data that can be found in the company’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.

Date correct
August 2020
Policy areas