A CBA spokeswoman said the bank disagreed with the union's "flawed" survey, which was part of the union's EBA campaign, took the wellbeing of staff seriously and encouraged whistleblowers to come forward in the bank.

CBA is set to make a record profit this year of more than $8 billion. It is renegotiating its enterprise bargaining agreement with the union.

He said CBA was the "biggest and the baddest" of the banks. "Staff have to up-sell and on-sell products and services and debt to consumers to maximise profits for the bank."

FSU national secretary Leon Carter said 800 bank staff where interviewed for the survey in response to "repeated nationwide reports of workers at CBA experiencing stress at work".

Explosive new survey reveals the pressure faced by bank tellers to chase sales targets is leading to fraud at the CBA. Credit:Dominic Lorrimer

More than three-quarters of staff surveyed said they felt stressed about achieving their targets and more than half said they had to work overtime to achieve their targets. A Victorian-based staff member said linking sales and pay was "a broken system that can't be repaired" and was inappropriate given the trust customers place in banks.

In Queensland, a staff member said they recently discovered "again" staff were falsifying credit applications, which was "widespread in our area". The staff member said it was brought to the attention of management, who already knew about it. "Is this not fraud … Don't we get dismissed for this conduct? No satisfactory answer was given."

"When people are under pressure to achieve targets they will do these things," the staff member said. The CBA said it was "urgently" investigating the allegation.

The report comes as the Coalition introduced regulations to water down reforms to financial advice, effective from Monday.

More than half the staff surveyed said they did not know how targets were set. One staff member said: "Sadly the decay of CBA is upon us. In my branch there is not one staff member that feels satisfied with their job," another said. "It is becoming more and more exhausting trying to get targets and with the stress our customer experience score [customer satisfaction rating] is falling."