The charges customers pay to receive personal banking services are to come under scrutiny in a comprehensive investigation by the Office of Fair Trading (OFT).
What began as an investigation into the fees banks charge customers who exceed overdraft limits or whose cheques bounce has now been extended and prolonged.
The watchdog's wider investigation will be "the most wide-ranging study into personal banking to date", a spokesperson told BBC News.
It will explore the so-called 'waterbed' effect whereby outlawing high fees in one area may displace fee-charging onto customers elsewhere.
A broader investigation "will provide the necessary context for assessing the fairness of unauthorised overdraft and returned item charges before we apply the law in this area", explained OFT chief executive John Fingleton.
It will emphasise that customers and banking providers are in a reciprocal relationship with mutual obligations.
"We want greater transparency in what you get and what the charges are," the OFT spokesperson told the BBC.
And as the public become more aware of the issues around free banking, they may also become aware of their own responsibility to stay within agreed limits.
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