A LITTLE-known superannuation law change could hit Australians hard, an academic has warned.

Queensland University of Technology legal and accounting expert Alastair MacAdam said changes to the anti-detriment benefit provided by many superannuation funds could cost thousands.

"We've been told that the Federal Government's superannuation changes will affect only 4% of people," he said.

"But removal of the superannuation anti-detriment benefit will affect many ordinary people who have a spouse or dependent children - even people on modest government schemes could lose $100,000 or more. It applies to everyone."

Mr MacAdam said the anti-detriment payment was paid to an eligible spouse when a fund member died.

He described it as a "refund" of all the contribution tax and said it went to the dependant spouse and/or children on top of the balance of the super fund.

"For many people with modest superannuation balances this could be anything from $10,000 to $30,000 extra super that their dependents will miss out on after July 2017," he said.

Mr MacAdam said the removal of the payment had largely gone unnoticed by finance commentators.