FAMILIES are spending less on childcare as a percentage of their household budget than they were almost a decade ago because the increase in government assistance has outstripped price rises, modelling shows.
The figures bolster the case for the federal government's expenditure on childcare assistance payments, which will reach a record high of $22.3 billion over the next four years.
''Helping families is not only fair but makes good economic sense, particularly for those on low incomes,'' the Treasurer, Wayne Swan, said.
The analysis, by the Department of Employment, Education and Workplace Relations, found women on low to average incomes were more likely to return to work if given financial assistance with the cost of childcare.
High income women were less likely to consider government assistance as a factor when deciding when to return to work after having children because childcare costs did not form as great a part of the household budget.
Mr Swan said the tripling of the tax-free threshold had also been of particular benefit to ''mums picking up some part-time work''.
''These are the super mums, the mums who have the responsibilities of raising children and going to work and earning an income.''
The figures come despite increased attention on the rising annual cost of childcare which, in some states, is being blamed on the federal government's attempt to improve the standard and quality of care.
The department's modelling shows a family on a combined income of about $100,000 spent less on out-of-pocket childcare costs last year than in 2004.
Last year a two-parent family with one child in full-time childcare spent an average of 7.5 per cent of its disposable income on care costs. In 2004 it was 13.4 per cent.
Despite yearly increases in the cost of childcare a family with a combined income of $135,000 spent 8.3 per cent of its income on childcare last year, compared to 10 per cent in 2004.
The difference is due to a boost in the childcare rebate from 30 per cent to 50 per cent of out-of-pocket costs, which was introduced by the Labor government when it came to office in 2007.
The government also gave people the opportunity to receive the rebate fortnightly or quarterly instead of as a lump sum at the end of the financial year.
The department's economists concluded that the earlier version of the rebate was not factored into families' budgets because ''there was a considerable lag between the incurring of childcare expenses and the receipt of any rebate''.
Therefore it had not acted as an effective incentive to encouraging women back to work after having children, the paper concluded.
The government's multibillion-dollar expenditure is paid to families through two payments - the means-tested childcare benefit and the non-means tested rebate, which is capped at $7500 per child per year.
It is an investment the government sees as vital to getting as many women with children back into the workforce.
Australia has one of the highest gaps between workforce participation of women with children compared with women without children in the developed world.