However, the energy supplier will also pass on the savings to customers who are on fixed and capped tariffs, as well as those on variable tariffs.
The cut will be an average of 3.5 per cent from 24 March 2014, and will equate to £38 for the typical customer.
SSE will also pass on a £12 rebate to customers as a result of the Warm Home Discount being moved into general taxation.
The £50 reduction comes after the supplier announced an average 8.2 per cent (£106) increase to average dual fuel bills, which came into force in November last year.
Will Morris, group managing director for retail at SSE, said: “When costs go up, prices eventually have to go up. When costs come down, so can prices. It’s that simple.”
He added: “As well as cutting prices in the short term, we have also promised to cap our prices at the new, lower level until Spring 2015, subject to there being no marked and sustained increase in wholesale energy costs, network costs or new policy-related costs.
“This reflects the fact that a significant amount of the upward pressure on energy bills has been removed by the Government’s action to bring down costs.”
The savings will be implemented from 16 June and backdated to cover the entire period from 24 March, based on customers’ consumption.
The move means that Npower is the only major supplier yet to announce details of how it will pass on the savings from changes to the social and environmental levies to its consumers.