A report by the federal government found no matter what the income level, Canberra families were paying the highest percentage of their income on out-of-pocket costs for centre-based long-day care. That was both before and after subsidies were paid.

The report, by the Department of Education, Employment and Workplace Relations, put out-of-pocket expenses for Canberra families for childcare consistently above the national average and at the highest percentage across income levels from $35,000 to $150,000.

In the ACT, childcare generally accounted for about 12 per cent of gross income after subsidies while the Australian average was around 8 to 9 per cent.

It comes as some long-day centres in Canberra prepare to put up their fees next year and some have reached or surpassed the $100 a day mark.

Fees for long-day care in Canberra can range from about $80 - but food and nappies are not included and must be provided by families - to up to $105 or $107 a day. The size of the centre also affects fees.

Other centres are nudging the $100 a day mark.

But one operator, who did not want to be named, said government subsidies which cut fees by half made the psychological barrier of $100 a day largely irrelevant.

Families can access the Child Care Rebate covering 50 per cent of out-of-pocket childcare costs, up to $7500 per child per year. Some families are also eligible for the Child Care Benefit that helps with the cost of childcare.

The childcare workers' union, United Voice, last year issued figures which showed the highest daily childcare cost in Canberra was just over $80. Union president Michael Crosby said despite fees increasing, the battle was still on for adequate wages for childcare workers.

The minimum rate of pay for a certificate III educator is $19.07 per hour while those with a diploma earn $22.46. United Voice says those rates are around $10 less than the average Australian wage.

''About 25 per cent of centres have got enterprise agreements but honestly the dispersion between award and enterprise agreement is pretty small. It's probably 3 to 4 per cent above the award,'' Mr Crosby said.

''It doesn't matter where you go, these workers are low paid … the community is not paying enough for people doing an essential job.''

Mr Crosby said despite rising fees, childcare was an expensive business to run, particularly in providing the required educator to children ratio. Real estate costs were also a factor.

''It's much more expensive to run a long-day centre than it is to run a school,'' he said.

The federal government has asked the Productivity Commission to conduct an inquiry into childcare ''with a focus on developing a system that supports workforce participation and addresses children's learning and development needs''.

However, the government's decision to withdraw $300 million in

funding meant to bankroll pay rises for childcare workers has had an immediate effect. One Canberra operator, who runs four centres, lost out on $1.3 million over three years for its staff.

Mr Crosby said United Voice has also gone to the Fair Work Commission asking it to review the wages in long-day care, alleging that childcare work was ''undervalued because it's done by women'', with 97 per cent of the workforce female.

The first substantive hearing is in March and United Voice was asking the commission to award at least $10 an hour more to educators.

''I think we've got a really good case,'' he said.

''The question in the minds of our members, then, is who is going to pay for the increase?

If we just get that wage increase and nothing else happens, then parents are going to pay that cost and our members are really strong that that's a cost that shouldn't be borne solely by parents.''

Mr Crosby said that meant the federal government contributing to topping up childcare worker wages, a message United Voice would put to the Productivity Commission inquiry.

''Tony Abbott, in his current mood, won't want to hear this but something has to give,'' he said.