Under new rules announced today, the Big Six energy suppliers will have to write to all of their customers once a year informing them if they are on the best type of tariff for their usage.

The new rules do not however, mean that the supplier has to inform their customer if there is a cheaper deal with another supplier – only if they would be better off on another of their own tariffs.

Deputy Prime Minister Nick Clegg however announced plans are also in the works to print barcodes on consumers’ bills, which will be easily scanned by a smart phone, allowing easy comparison between tariffs.

The Big Six energy suppliers are British Gas, EDF Energy, E.ON, NPower, SSE and ScottishPower. Between them they control a 99% share in the consumer energy market.

Currently 7 out of 10 households are on a tariff that doesn’t suit their needs as well as it could, as there are over 120 tariffs to choose from.