If you are on the Standard Variable Rate and have never switched, it's likely you will save between £100 and £300 a year.
A recent investigation by the government's Competition & Markets Authority found that two-thirds of 'big six' customers are still on expensive standard tariffs, paying an estimated £1.4 billion a year more than they would on more competitive rates.
The big six suppliers are British Gas, SSE, Scottish Power, EDF, E.ON and Npower. According to MoneySavingExpert.com, the average annual duel-fuel bill from a 'big six' supplier on 21 July 2017 was £1,138. But the cheapest deal available would have cost just £844.
A Spokesperson for Ofgem said: “You can save up to £300 per year from switching supplier. You can also switch to another supplier if they have a better customer service rating."
Almost a third of UK households have never switched, but people are becoming more aware. Energy UK reported that 2016 was a record year, with 4.8 million people switching. Switching should be straightforward: There's no change to the actual gas or electricity you get, just to the company. Your energy supply won't be interrupted.