Experts have warned families are in danger of being hit with unexpectedly huge bills after a shock poll revealed most people do not understand the government's energy price guarantee.
Exclusive polling by Savanta ComRes for Yahoo News UK found three in five Brits are unaware of how energy bills are being capped by the government.
The energy price guarantee limits the price per unit of energy that consumers can be charged, but does not impose a cap on how high a total bill can go.
It means a typical household will pay around £2,500 per year, although some homes will face bigger bills if they use more gas or electricity.
Asked if the statement "Government support means no household is having to pay more than £2,500 per year on their energy bills at the moment" was accurate, 46% of people polled said it was true, and 15% of people said they didn't know. Just 39% correctly said it was false.
The polling highlights government failings - under both Liz Truss and now Rishi Sunak - at clearly explaining how the support package works.
Responding to the poll, Martin Lewis told Yahoo News UK described it as a "cock-up".
Campaigners also warned of the potentially devastating impact on bill payers.
“The energy price guarantee is a vital intervention, especially in light of Ofgem’s latest price cap level announcement – average yearly bills will be over £1,700 less than they could otherwise have been from January onwards without this support," campaigning group National Energy Action told Yahoo.
"However, ‘average’ is the key word here and the UK government's initial messaging on this point was not at all clear. This research shows there continues to be a huge level of misunderstanding around this policy.
"Two thirds of people not understanding this key nuance could lead to households thinking that they can use as much energy as they like and then being hit with an unexpectedly high bill.
"There are also big differences depending on how households pay for their fuel bills, of which there remains very low awareness among the public.”
The polling for Yahoo News UK shows the public have a better understanding of some of the other aspects of the energy price guarantee.
81% of people correctly believed the cap will rise to £3,000 in April, with 61% correctly believing the government has capped the unit price of energy.
Money Saving Expert Martin Lewis told Yahoo News UK said the issue needed to be addressed.
"We have to make sure people, especially vulnerable people, understand that there is no total cap on what you can pay on energy bills," he said.
"The risk is two-fold, first people may wrongly think if they're near the limit, they can use as much energy as they like and not pay more. Plus it also reduces the incentive to fit energy efficiency measures.
"I know from private conversations with the government machine, that when this was being miscommunicated by the former prime minister, they were unhappy for these reasons.
"It was definitely more cock-up than conspiracy."
The energy price guarantee was introduced by Liz Truss in September in response to soaring energy bills following Vladimir Putin's invasion of Ukraine.
Truss was widely criticised after she repeatedly claimed no household would pay more than £2,500 a year for the energy bills.
The department for business, energy, and industrial strategy (BEIS) has been approached for comment.
How does the energy price guarantee work?
The energy price guarantee caps the price suppliers can charge households per unit of energy.
The level the cap has been set means the average household's bill will be around £2,500 a year. Annual bills can be considerably higher or lower than this depending on how much energy is used.
The scheme is separate from the energy bills support scheme, which provides a £400 payment to eligible households from October 2022 to March 2023
The energy price guarantee means the average household's bill will be roughly £1,000 lower than it would have been without the intervention, and the government will pay the difference.
It is applied automatically and there is no need to apply for the cap.
Families who are not connected to the mains gas and electricity network, such as those who use heating oil, receive separate funding.
The support is in place until April, at which point a new higher cap will come into force, and the average household will pay around £3,000 a year for energy.
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