The average annual rise for customers who don’t switch will be 14.28 per cent the comparison company says, with 12 of the 16 tariffs that end on 31 May rolling customers onto a more expensive variable tariff, unless they shop around for a new tariff.
Big six supplier Npower’s customers currently on its Price Fix May 2016 tariff will see the largest average annual rise of £193.26.
First Utility customers in the Norweb region on the iSave Fixed May 2016 v3 tariff will experience the largest regional rise of £380.13.
Gocompare energy spokesperson Ben Wilson said: “It’s easy to forget about energy tariffs when our usage drops in the summer. However when it comes to your gas and electricity bills, taking your eye off the ball could cost you hundreds of pounds.”
Customers of some suppliers including Co-operative Energy and M&S Energy will save when switched to the supplier’s variable tariff by an average of 3.9 per cent.
TABLE: top ten cheapest dual fuel tariffs
Source: Gocompare.com