Energy consultant Cornwall Insight said a regular gas and electricity bill in England, Wales and Scotland could reach £3,615 in the new year, which is hundreds of pounds more than previous predictions.
In May, the Government announced an energy costs support package – worth £400 per household – in response to predictions that bills would rise to £2,800 for the average household in October.
Last month, Cornwall Insight predicted that annual energy bills would typically rise to £3,244 from October and £3,363 from January, but circumstances have changed significantly since then.
The truth is the £400 pledged will only scratch the surface of this problem
Craig Lowrey, Cornwall Insight
The company told BBC Breakfast that such a bill is now likely to rise to £3,358 from October and £3,615 from January.
Cornwall Insight’s principal consultant, Craig Lowrey, said surging gas prices and concerns about Russian supply had prompted the increase.
“However, while the rise in forecasts for October and January is a pressing concern, it is not only the level – but the duration – of the rises that makes these new forecasts so devastating,” he told the programme.
“Given the current level of the wholesale price, this level of household energy bills currently shows little sign of abating into 2024.”
Dr Lowrey joined other experts in saying Government support will “only scratch the surface” for households.
“While the Government has pledged some support for October’s energy rise, our cap forecast has increased by over £500 since the funding was proposed, and the truth is the £400 pledged will only scratch the surface of this problem.”
On Friday, Richard Neudegg, director of regulation at Uswitch, called for the £400 to be increased to at least £600, and for payments to vulnerable households to rise from £650 to £950.
“The Government did the right thing by stepping in with wide-reaching support to try to help ease the blow. However, this support now looks like a severe under-estimation of what consumers need,” he said.
“Households need clarity to help them plan for the most expensive winter in living memory.”
Charity National Energy Action last month predicted that, should the average bill reach £3,250 per year, 8.2 million UK households will be in fuel poverty, or one in three.