The extra costs faced by energy customers when a one-year deal comes to an end varies widely, analysis by one provider has revealed.

Prices rise when customers are moved onto a variable tariff at the end of a one-year deal, unless they switch. This increase ranged from £275 to nearly £350 a year for the average household using one of the UK's major suppliers - known as the big six. Extra charges from some smaller suppliers were £30 a year or less. Prof Catherine Waddams, of Norwich Business School and an expert on energy pricing, expressed surprise at the size of the differences. "Some companies depend on it much more than others, particularly the big six," she said....

Source: Read more here