Bill Shorten has refused to admit Labor's childcare policy will give millionaire parents an annual taxpayer-funded subsidy of $10,000.
Federal Labor wants to retain existing childcare payments - described by the Productivity Commission as overly complex - but increase the amount parents get.
This would lift the means-tested child care benefit by 15 per cent and raise the annual cap on the child care rebate for every parent from $7500 to $10,000.
Both measures would kick in from January 1, 2017, if Labor wins government on July 2.
"Labor's childcare policy is a ripper," the opposition leader told reporters in Adelaide on Tuesday when asked whether it failed his own fairness test.
Mr Shorten was twice asked to admit the policy gave $10,000 to millionaire parents, especially in light of his criticism about the government's decision to end the temporary budget repair levy on high-income earners.
Instead he attacked the government's plan for an activity test that requires parents to work at least eight hours a fortnight to qualify for subsidies.
Mr Shorten said that was unfair to women in casual or insecure work.
"This country cannot afford to be putting disincentives in the path of people working."
The coalition government argues Labor's plan to increase subsidies is likely to end in higher childcare fees and doesn't set the system up for long-term sustainability.
It intends putting a cap on the amount paid to childcare providers, although parents can claim for as many hours as they qualify for.
