Energy Secretary Ed Davey, is to outline government plans to fulfil the pledge made by David Cameron last month, to bring in legislation to force energy companies to offer their customers the lowest possible energy tariff.
He will also instruct the energy companies to reduce the number of tariffs to just four each for electricity and gas in a bid to end the confusing number of tariffs offered at present.
The new tariffs will be: A fixed price for a fixed term, a standard variable rate with two others based on other criteria such as method of payment or renewable energy.
However, Labour said the cheapest deal in an uncompetitive market will still not be a good deal.
Under the new proposals, energy companies would be forced to switch customers automatically to the lowest suitable tariff unless they objected.
The real test will be whether people actually see smaller bills at a time when energy prices are rising.
Currently most people buy their gas and electricity from just six big suppliers, although there are smaller suppliers and a huge choice of tariffs.
