Opposition spokeswoman Amanda Rishworth says such incentives may lure parents into childcare arrangements that may not suit their needs.

The commonwealth is due to spend $7.9 billion on the childcare subsidy this year and that money should be going towards helping families afford such services, not on enrolment rewards, she said.

"We don't think that has any place in our early year system," Ms Rishworth told reporters at a childcare centre in Sydney on Monday.

"The commonwealth invests such a huge amount in the early years and we don't want to see that used to mislead parents or trap them into contracts using non-educational inducements."

Recent reports suggest childcare and early learning centres have gone to "alarming lengths" to attract new recruits, Ms Rishworth said, including offering free iPads, holiday packages and cash refunds.

Labor's plan would ban childcare providers from offering any goods, services or activity unrelated to the delivery of their services.

Those who didn't comply would be stripped of the childcare subsidy.

Families and educators would also be able to confidentially tell the Department of Education and Training about any incentives or behaviour they suspect is an inappropriate inducement.

The commitment comes as Labor has renewed efforts to highlight the impact of what it says have been cuts to childcare under the coalition.

Speaking in the Wentworth electorate, Deputy Labor Leader Tanya Plibersek said about 3500 families would be worse off under federal government changes to the funding formula.

"We know across the country that thousands of Australian families will be worse off."

Education Minister Dan Tehan has been contacted for comment.

Australian Associated Press