Energy bills could soar by up to 54 per cent in hundreds of thousands of households when many popular fixed deals expire at the end of the month.
Consumers are being warned their bills could rise by up to £414 if their supplier automatically puts them on a more expensive new tariff.
It comes as many big energy firms have already announced further price increases this year.
Consumers are being warned their bills could rise by up to £414 if their supplier automatically puts them on a more expensive new tariff
With a total of 16 popular fixed deals from seven suppliers due to end on April 30, customers are being urged to shop around to avoid hefty increases.
Those on the fixed tariffs scheduled to expire are likely to be put on to more expensive standard variable tariffs if they take no action, according to the energy price comparison website uSwitch.
Fixed energy tariff customers with Npower face paying £414 more on average, while those with First Utility could be stung by an extra £397 and ScottishPower users £373 more, the consumer site warned.
Co-operative Energy, GnERGY, EDF Energy and Flow Energy also all have fixed deals expiring this month.
Claire Osborne, uSwitch energy expert, said: ‘With many popular fixed deals ending this month, it’s more important than ever to avoid being rolled on to sky-high tariffs.
‘Not only do some consumers face a hefty price hike after their fixed deal ends, but they could also be stung by recent price rises to standard variable plans if they take no action.
‘Customers on these deals can switch now without incurring any exit fees, avoid expensive standard tariffs and safeguard against further price hikes.’
Six out of the seven suppliers with deals ending this month have also already said they will increase prices this year.
EDF Energy recently announced its second rise of 2017, adding £78 to its standard variable tariff from June, while Npower’s standard tariff has risen on average by £109 and E.ON is due to increase by £97.
Fixed price energy tariffs – which usually last 12 months – guarantee customers the price of their energy will not increase until the end of the plan.
With a total of 16 popular fixed deals from seven suppliers due to end on April 30, customers are being urged to shop around to avoid hefty increases
Energy suppliers are required by Ofgem to write to customers between 49 and 42 days before their fixed deal expires to let them know they can switch tariffs or suppliers free of charge.
If they do not respond, customers are put on the cheapest variable rate available – typically the supplier’s more costly standard tariff.
However, Ofgem is considering plans that would mean suppliers automatically have to put consumers back on a fixed tariff if it is the cheapest option available.
A spokesman for the energy watchdog said last night: ‘Our advice to customers is that it is good to shop around and check you are on the best tariff for you.’
He added: ‘We have consulted on changing the rules for what happens at the end of a fixed-term contract, so that suppliers should be allowed to move a customer who has not made an active choice on to another fixed deal rather than a standard evergreen tariff – so long as it was a cheaper option and the customer was able to exit this tariff with no penalty and at any time.
‘This could help customers as standard variable deals are often the suppliers’ most expensive tariffs.’
The watchdog has yet to make a decision on the proposal.
A spokesman for First Utility said last night: ‘A very small minority of First Utility customers transition on to the (standard variable tariff) once their fixed contract ends, and those that do are on it for a matter of months before moving to a better-value fixed plan.’