The hike, which applies to both electricity and gas, will mean bills for a typical dual fuel domestic customer on the SVT will rise by an average of 5.5% a year.
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British Gas said the price increase is largely due to rising wholesale gas, electricity and policy costs and will impact 4.1mln SVT customers.
However, the firm said, 3.7mln customers on fixed-term contracts, prepayment meters and vulnerable customers will be unaffected by the price increase.
British Gas said its SVT default tariff was withdrawn for new customers on March 31, with all existing customers being encouraged to choose one of the firm’s fixed-term deals.
Customers who do not make an active choice when their existing fixed-term tariff ends will move onto a 12-month fixed term default tariff, which will also increase by £60 to £1,136 a year on May 29.
Mark Hodges, chief executive of Centrica Consumer, said the price increase was beyond the firm’s control: “We fully understand that any price increase adds extra pressure on customers’ household bills.”
He added: “We believe Government should level the playing field so the customers of all suppliers pay a fair share of energy policy costs.”