npower’s dual fuel customers who saw their energy bills increase in December 2013 will typically see a £50 reduction in their annual energy bill starting from 28 February.

This includes those on discounted fixed-term tariffs, made up of the npower tariff change of £38 and then the universal rebate of £12 in the Autumn.

Customers on fixed or variable price dual fuel or electricity only tariffs who did not experience a bill increase in December will receive the Government’s £12 universal rebate.

In December, the Government announced that it will reduce the green levy commitments of the UK’s energy companies in a bid to lower fuel bills for households.

Earlier this week Scottish Power announced it is to reduce energy bills by 3.3% from 31 January.

SSE also confirmed it is to cut its prices by 3.5% from 24 March.

E.ON and EDF have also unveiled price reductions.

Clare Francis, editor-in-chief at MoneySuperMarket, said: “npower is the last of the Big Six energy giants to confirm how it will respond to the Government’s reduction in green levies and it’s hugely disappointing that only two – British Gas and SSE – are doing the right thing by customers. Customers of npower, Scottish Power, EDF Energy and E.ON who have fixed rate deals will only receive a £12 rebate from the changes to the Warm Home Discount Scheme – they won’t benefit from the cut in green levies.

“Whichever way you look at it, the Government announcement was intended to benefit all bill payers. This is hardly treating customers fairly, and those being penalised are the ones who have done the right thing and taken action against spiralling bills by fixing their energy prices. These customers will still probably be paying less than those on variable rate deals, but that is not the point: they should still benefit from the Government’s reduction in green levies as this will have been built in to the pricing of those tariffs also.”