A "national discussion" is needed about the cost of the National Disability Insurance Scheme, federal minister Linda Reynolds has said, as she prepares to start renegotiating funding deals with the states and territories.
The Morrison government is adamant the scheme's rate of growth is unsustainable and steps must be taken to preserve it for future generations.
The agency in charge of the scheme has already set up a taskforce to slow growth in participant numbers and funding packages.
But Senator Reynolds remains open-minded about how much should be spent on the NDIS, saying that was "a discussionfor us to have as Australians".
"I make no judgement about what the broader Australian society wants in terms of the allocation of their taxes," she told Australian Community Media.
"But it is a conversation we have to have because it is [the NDIS] becoming far more expensive for state or federal taxpayers."
The May federal budget included dramatic revisions in the NDIS's projected cost from just seven months earlier, forecasting the bill for participant supports would now approach $32 billion by 2024-25.
The growth is being driven by an increase in individual budgets and the number of participants entering the scheme. The NDIS is now expected to support 530,000 Australians with significant and permanent disability - about 55,000 more than had been anticipated.
Senator Reynolds has made repeated mention in recent weeks that the scheme is on track to surpass the cost of Medicare.
That argument has been attacked by advocates, who have accused the Morrison government of hyping up the scheme's growth as out of control in an attempt to garner political and the public's support for deep cost cuts.
The comparison to Medicare has also been described as misleading, given that unlike the healthcare program the costs of the NDIS are split between the Commonwealth and states and territories.
The government's argument ahead of the budget that the scheme was growing beyond expectations was called into question, with advocates, Labor and the Greens arguing costs were largely in line with the Productivity Commission's estimates.
But the projections contained in the agency's latest quarterly, published after the budget on May 20, far exceeded what the commission had forecast - predicting that on its current trajectory the NDIS could potentially cost $40 billion within three years.
The budget has allocated more than $29 billion in 2023-24, meaning there is a $10 billion gap between what the government has set aside and what the agency believes the scheme could cost at that point.
Senator Reynolds said the agency's projections assumed that no action would be taken to curb cost increases.
With those figures on the table, she said it was now up to states, territories and the Commonwealth - and Australian taxpayers - to determine how much they were willing to spend on the scheme.
Senator Reynolds reiterated Treasurer Josh Frydenberg's statement on budget night that the scheme would always be "fully funded" under the Coalition.
She said negotiations with the states on individual funding agreements were due to start in 2022.
Senator Reynolds has not ruled out asking the states to contribute a greater share of costs, saying "these were the discussions we'll have to have".
"The conversation that now has to be had, it is a national discussion. It has to be, because it's Australian taxpayers' money, but also it is a scheme that any one of us might need to draw on," she said.
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