Falling energy prices come with a catch – unless you supply your provider with a meter reading on or around the date of the price cut, you could be overcharged. This is because consumption is typically overestimated by providers, most of which take infrequent meter readings.

When, as now, many of them reduce their charges, they rely on estimated usage that could be out of date or inaccurate. If months go by before later meter readings are taken, showing the customer used less energy than expected over the whole period, the provider cannot tell how much to charge at what rate. Inevitably, consumers are overcharged.

Consumer watchdog Which? estimates £4million a year is creamed off by providers due to estimated meter readings and billing mistakes.

Eon recently announced it would cut electricity charges by six per cent from February 27. Scottish Power will cut its gas bills by five per cent from the same date. EDF is also cutting gas prices by five per cent from February 7 while British Gas has already cut electricity bills by five per cent. SSE is to cut gas bills by 4.5 per cent on March 26 and npower is cutting its gas prices by five per cent at the start of next month. Co-op Energy is slashing three per cent off both electricity and gas bills from the start of the month while Ovo Energy cut dual-fuel gas and electricity bills by five per cent earlier this month.

James Tallack, a policy adviser at Which?, says: ‘If a tariff changes and you don’t know the actual energy you have used, it is easy to get overcharged – the only way to avoid it is to provide a meter reading on the day of the price change.

‘Providers must notify any tariff changes by letter within 30 days, but it is still up to the customer to provide the accurate reading.’