The treasurer has defended possible changes to tax breaks on multimillion-dollar superannuation balances as reasonable measures that won't alter the fundamentals of Australia's retirement savings system.
Jim Chalmers said the changes under consideration, which could include a cap on large super balances attracting concessional tax treatments, were not "especially controversial".
He said they were similar in scope to "tweaks" made by the former coalition government while in office, including changes to superannuation taxes in 2016 that raised $5 billion.