Free childcare has so far cost the government just under $1 billion, but the minister responsible has signalled it won't last past the end of June.
A Senate inquiry scrutinising the government's response to the coronavirus pandemic heard the emergency funding model for childcare centres, where they were funded a flat 50 per cent of their usual fees instead of subsidies based on family incomes, was costing $131 million a week.
So far $917 million has been spent and it is expected $1.6 billion will be spent over 12 weeks up until June 28.
Officials didn't say how this compared to the previous funding model, but said the full year of childcare had been budgeted at $8.3 billion.
Most childcare centres are also receiving funding through the JobKeeper wage subsidies, although officials said their modelling showed some centres and staff members wouldn't be eligible to the program.
Education Minister Dan Tehan released a summary report into the implementation of the funding model on Tuesday, which found that 99 per cent of childcare centres were able to remain open, and more than 80 per cent said the government's package allowed them to stay open and retain staff.
Despite extensive media coverage of the report on Tuesday, departmental official Ros Baxter said the document couldn't be released to the Senate committee as it had been part of cabinet deliberations.
As well as the new funding model and the JobKeeper payment, childcare centres have also been able to apply for exceptional circumstances funding, with 1559 centres applying for the payments worth more than $24 million.
More than 800 services have been approved for the payments and Labor senator Katy Gallagher questioned how many centres had been knocked back and called for more clarity around how decisions are made around the fund.
Under the special arrangements, the government is guaranteeing childcare operators their taxpayer funding as it stood in late February - about half their usual revenue - plus the JobKeeper wage subsidy to those eligible.
But they can't charge parents the usual gap fee.
The review found about three-quarters of centres said this was keeping them financially viable.
Seven in eight services had applied for JobKeeper.
Of those who didn't apply, about a third were run by independent schools or not-for-profits like Anglicare and weren't eligible but can now access top-up funding.
Some services that were eligible found the wage subsidy didn't cover many of their staff.
In general, centres were able to meet the demand for places although some were doing so at a loss.
On average, attendance was less than two-thirds of pre-virus levels.
Many centres worried about meeting the increased demand for places and having more children attend as the economy starts reopening.
They wanted a month's notice before the system reverted.
Education Minister Dan Tehan said the government would keep a close eye on this.
"The four-week review into the package makes clear that we need to begin planning for increased demand for places as businesses re-open and more people return to work," he said.
"The review suggests a need to consider how the relief package can support economic recovery, supporting parents to get back to work and study, and children's early childhood education and wellbeing."