Concerns about energy provider SSE's approach to switching its customers – and particularly those in vulnerable situations – onto prepay meter tariffs has sparked an investigation by the energy regulator.

Ofgem will examine whether SSE breached its standards of conduct, which are aimed at ensuring suppliers treat customers fairly.

It will also investigate if SSE breached licence conditions, which require it to provide appropriate information to customers – such as the pros and cons of prepayment meters – and consider consumers' ability to pay when informing them of alternative payment methods.

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I'm on a prepay meter tariff with SSE, can I provide evidence to this investigation?

We asked Ofgem whether it'll be open to receiving anecdotal evidence from consumers, but were told that this is not something it would encourage at this stage.

A spokesperson told us the regulator will first be speaking to "key stakeholders" from the energy market before making any judgements.

The investigation was launched today, but Ofgem declined to comment when asked for more details about its timeframe.

What does SSE say?

"We are committed to treating all our customers fairly and will be cooperating fully with Ofgem's investigation into this historic issue."

SSE probe hot on the heels of competition watchdog's energy report

This Ofgem investigation into SSE follows a wider probe into the energy market by the Competition and Markets Authority (CMA).

The CMA issued its final report last month in which a temporary price cap on prepaid tariffs was ordered.

SSE under investigation over switching vulnerable customers to prepay meters
Ofgem will examine whether SSE breached its standards of conduct, aimed at ensuring suppliers treat customers fairly
The report stated that a price cap will be brought in for a "transitional period" between 2017 and 2020, meaning there will be a maximum rate those who prepay for gas or electricity can be charged. 

The CMA claimed that if this cap had been brought in last year, the average prepaid energy bill would have fallen by around £75 a year.

Earlier this year, responded to the CMA's provisional decision on remedies by welcoming the prepay cap, while MSE founder Martin Lewis has also previously thrown his support behind a cap.

Following the publication of the CMA's provisional decision on remedies back in March, Martin said: "I welcome the cap on prepayment meter charges. While we've heard spurious claims before that they are no longer more expensive, that's baloney – typically prepayment customers are paying massively more than those on dual fuel in a market that isn't competitive. So it's very important that these people are protected as they tend to include some of the most vulnerable and poorest in society.

"The new cap should at least mean they are not paying extremely over the odds. What I also want to see though is the ability for everyone who is on a prepayment meter, once they qualify for a normal meter, to be able to switch without cost. That is what will truly change the market and unlock people from the prepayment prison."