The federal government is considering scrapping the $7500 cap on childcare rebates in exchange for cutting back the rebate for wealthy families.

Social Services Minister Scott Morrison has received feedback from well-off parents that the cap was an inhibitor to workforce participation.

"For higher income earners, people earning over $180,000 in family income, what is more important to those families ... is the inflexibility of the cap rather than the level of subsidy," he told News Corp Australia.

Mr Morrison is yet to make a formal decision.

But key crossbencher David Leyonhjelm is outraged by the prospect of taxpayers forking out increased subsidies for childcare, saying it was unfair to childless people.

"Having kids is not a social service that governments should subsidise, it is a choice," the Liberal Democratic Party senator said in a statement.