Shadow treasurer Chris Bowen has dismissed criticism of Labor's negative gearing policy, insisting the major economic reform would not worsen housing affordability or unfairly hit middle-class investors.

Mr Bowen said the attacks from Treasurer Scott Morrison, the housing lobby and some economists amounted to falsehoods and myths.

"The proponents of the current arrangement say negative gearing increases housing supply. It doesn't; it's a falsehood," he told the ABC's Insiders program on Sunday.

"Ninety-three per cent goes into existing properties and that means, in effect, if [increasing the housing supply is] your policy objective, you've got a failure rate of 93 per cent."