Millions of homes across the UK are already in debt over their energy bills, with £1.3 billion owed to suppliers two months before bills are set to soar by more than 80%.
The overall debt is already three times higher than it was a year ago, according to analysts at Uswitch, and it is expected this will grow even further over the winter.
Six million UK homes owe an average of £206 to their energy provider, a survey from the company suggests. In April, the same average debt was £188.
It comes as regulator Ofgem is expected to hike the price cap on energy bills to £3,582 per year for the average household in Great Britain from October, according to a new forecast.
Analysts at Cornwall Insight predicted further rises to £4,266 in January, with the average household paying £355 per month, followed by another increase to £4,427 from the start of April.
Justina Miltienyte, head of policy at Uswitch, said: “Energy debt has hit an all-time high with the worst possible timing, turning this winter’s energy price hike into a deeply precarious situation for many households.
“This is an alarming situation, as summer is traditionally a time when households are using less power for heating, which helps bill payers to build up energy credit ahead of the winter.”
The survey also showed that eight million households have no credit balances, meaning they have no cushion against the winter costs.
Nearly one in five people (18%) said they are worried about their supplier forcing them to take a prepayment meter if they fall behind on bills, while 38% said they did not know their supplier could do this.
Ms Miltienyte added: “If you are behind on your bill payments, or your energy account is going into debt, speak to your provider as soon as possible.
“They should be able to help you find a solution, such as working out a more affordable payment plan. You may also find you are eligible for additional support such as hardship funds and other energy help schemes.
“The government also needs to take energy debt seriously ahead of the winter – and a greater support package for vulnerable households needs to be agreed as a priority.”
Energy bosses in crisis talks
Energy sector bosses are to take part in crisis talks with Chancellor Nadhim Zahawi and Business Secretary Kwasi Kwarteng as the price cap was forecast to hit more than £4,200 in January.
It follows widespread anger at Shell, BP and British Gas owner Centrica announcing bumper financial results while households struggle to cope with soaring bills.
Gas and electricity executives are expected to meet with the Cabinet ministers on Thursday morning (11 August), when the bosses will be asked to submit a breakdown of expected profits and payouts as well as investment plans for the next three years.
The government has already promised £400 to every household and extra help for the more vulnerable and energy bills have become a key focus of the Tory leadership campaign.
Money Saving Expert’s Martin Lewis called on Liz Truss and Rishi Sunak to tackle the problem together after warning the country was facing a "national cataclysm".
He said the "zombie government needs to wake up sooner than 5 September", when the new Tory leader and Prime Minister will be announced, as the new winter bill forecasts are "unaffordable for millions".