When you count down the start of 2015 on New Year’s Eve, you could also be counting down the end of your electricity tariff – and being bumped onto a higher one.

There are 13 fixed energy tariffs which expire on 31 December, from EDF Energy, M&S Energy, Npower, SSE, ScottishPower and iSupplyEnergy.

Experts say this could mean some people end up paying nearly 8% more than if they switched to a better deal.

Customers living in the Eastern distribution area – which includes East Anglia and Greater London – who are on ScottishPower’s Online Fixed Price Energy December 2014 tariff, can expect to be walloped with the biggest bill increase of £144.93, when they are moved onto the energy firm’s £1,177.32 standard tariff.

Jeremy Cryer, energy spokesperson for Gocompare.com advised people to start looking for a better deal “immediately”.

He said: “There are lots of good deals to be had right now and they are certainly a far better option than any supplier’s standard tariff. In fact, there are nine sub-£1,000 a year dual fuel tariffs available at the moment.”