Question to the Department for Business, Energy and Industrial Strategy:

To ask the Secretary of State for Business, Energy and Industrial Strategy, what proportion of customers of the Big Six energy companies have been on their supplier's standard variable tariff for each year from 2006 to 2016.

The Government wants to see energy companies treating all of their customers fairly, including those on Standard Variable tariffs, not just those who switch.

The Department of Business, Energy and Industrial Strategy (BEIS) collects data, including customers’ tariff information, from energy companies as part of the domestic fuels inquiry (DFI). In the second quarter of 2016, 69 per cent of domestic standard electricity customers and 67 per cent of domestic gas customers were on variable tariffs. This data is published within our Quarterly Energy Prices publication and can be found in Tables 2.4.2 and 2.5.2 which is available online: https://www.gov.uk/government/statistical-data-sets/annual-domestic-energy-price-statistics.

BEIS started collecting this data at the end of 2012; therefore annual data is available for 2013 onwards. These figures are based on the DFI which covers around 85 per cent of the market. This includes all of the big 6 energy suppliers, Northern Ireland suppliers and one smaller supplier. The proportion of customers on variable tariffs, including standard variable tariffs, is as follows: