More than a quarter of a million households face soaring energy bills if they do not switch tariff soon, new research has revealed. Some 167 fixed tariffs end this month which will see customers automatically switched onto more expensive 'default' deals if they do not switch tariff or provider when their plan comes to an end. The average increase to energy bills is £67 per household with the average annual cost of a fixed rate energy tariff ending in February coming in at £918, according to Compare the Market. If customers do not switch when their fixed tariff ends, energy companies are set to benefit from a huge 'inertia windfall'.