More than a million British Gas customers will benefit from a small fall in their bills as the company implements a plan to reduce prepayment meter charges ahead of time.

From Saturday, prepayment meter customers will pay as much as direct debit customers for gas and keep the same current discount for electricity prepayment meters, British Gas said.

It means the average customer getting both gas and electricity from one of the supplier’s prepayment meters will be £59 better off per year.

The Chancellor said earlier this month suppliers will be forced to slash the “prepayment penalty” – which sees gas customers with prepayment meters pay slightly more for their energy than direct debit customers.

The change is set to come into force from July, though British Gas said it will act earlier.

When not adjusted for the fact households use less energy during the warmer months, it will mean an average saving of a little under £15 per household over the three extra months.

We wanted to do more to support this group of customers by introducing this change as soon as we could so British Gas prepayment customers will benefit immediately

British Gas has around 1.24 million customers with prepayment meters. Around 158,000 only have electricity prepayment meters and will not benefit from the change.

Chris O’Shea, the boss of British Gas owner Centrica, said: “We know that more help is needed for prepayment customers and we support the Government’s decision to lower prepayment prices to the same level as direct debit customers.

“We wanted to do more to support this group of customers by introducing this change as soon as we could so British Gas prepayment customers will benefit immediately.”

The move comes as energy regulator Ofgem reviews how British Gas and others have been treating customers unable to pay their bills.

Data shows that more than 94,000 prepayment meters were forcibly installed last year without consent when a customer had not paid their bill.

Around seven in 10 of those installations were carried out on behalf of British Gas, Scottish Power or Ovo Energy.