Scottish Power is set to launch a prepay energy tariff that allows customers to pay for ‘days’ of gas and electricity.

Customers can buy up to 180 ‘days’ of gas or electricity, calculated from their previous usage. They can track usage via an app and will see how many days they have remaining. The tariff – which is ‘coming soon’ – will initially be available only to existing customers, who can register their interest online.

SSE, meanwhile, has made a bid for new customers by offering its cheapest deal exclusively to Energy Helpline customers.