It was found that while some energy providers had hidden costs for those who switch, others offered benefits such as charity donations and free repairs.
Alison Morrison, from Which?, said: "You can expect to receive the largest energy bill of the year after the winter period which is why now is an ideal time to look at switching.
"However, it's essential to read the terms and conditions of your contract to make sure you're not missing out on the best deals or weighing yourself down with extra costs or clauses."
Around half of the 2,000 respondents said they didn't read fully the terms and conditions.
This echoes the advice of the Citizens Advice Bureau which last month said consumers could save money by switching electricity provider.
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