Banks are being accused of gouging customers by delaying the transfer of superannuation accounts into lower cost default superannuation funds.
Under new rules, retail funds have been given four years to switch accounts nominated as "default" into cheaper My Super products with a deadline of 1 July 2017.
But research out today suggests bank-owned funds are dragging their feet by leaving default super in high cost legacy funds for as long as possible.
A study by Rainmaker Information commissioned by Industry Super Australia says banks are profiting by between $800 million and $1.8 billion in fees by stringing out the transition to approve default funds.
Rainmaker says given the aim of MySuper is to provide a default option for "disengaged passive members", the motivation of bank-owned funds need to be examined.
"The core question is to what extent have funds expedited this transition," the research suggests.
"This question is crucial because Rainmaker's annual superannuation fee surveys have revealed that MySuper products are on average 30% cheaper than regular corporate retail solutions.
"So the sooner members transition across to these lower cost products the sooner they start saving fees."
Industry Super Australia chief executive David Whiteley told the ABC's AM program the behaviour of bank-owned and retail funds was "unconscionable" and undermined public confidence in the compulsory superannuation system
"The retail and bank-owned super fund practice of leaving members' accounts languishing in more expensive legacy products requires greater scrutiny," Mr Whiteley said.
"The regulator would do well to ask if the product trustees are fulfilling their legal duties to put the interests of members over profits generated by wealth businesses inside the banks."
The research shows that although not for profit funds completed the transfers to MySuper by June 2014, retail funds are lagging with just 43 percent of funds switched by June 2016.
The Financial Services Council, which represents bank-owned and retail funds, maintains there is a clear timeline for the transfer to default funds.
FSC director of policy Andrew Bragg told the ABC that all existing money in the default super system must be transferred by June next year under longstanding legislation.
However, Mr Bragg said more competition was required as recommended by reviews conducted by Jeremy Cooper in 2010 and David Murray in 2014.