States on edge about NDIS cuts as Chalmers flags they will be ‘easily the most important’ part of budget savings

The states are increasingly on edge about Labor’s efforts to cut NDIS spending in next month’s budget, with officials asking the health minister, Mark Butler, to explain planned savings before a major speech this week.

It comes as the treasurer, Jim Chalmers, flagged on Monday morning that cuts to the NDIS will be “easily the most important part of the savings package that we will present on budget night”.

Butler will use an address to the National Press Club in Canberra on Wednesday to detail changes to the scheme’s growth rate, amid efforts to shore up its sustainability for Australians with a disability and their families.

But government sources in multiple states told Guardian Australia they were worried about the breadth of the changes and possible new costs for the states, after written requests for information to Butler’s departmental chief, Blair Comley, were rebuffed.

Western Australia, as the chair of the Council of the Australian Federation, the body that represents the states in negotiations with the federal government, communicated concerns from disability ministers about structural changes in recent days.

Multiple states reported being “blindsided” when Butler spoke at the Press Club last August, revealing without warning that a national scheme for foundational supports for children with autism and developmental delays would replace plans for state-led programs.

The Thriving Kids program, due to launch in October, is subject to joint agreements between state premiers and the federal government.

Victoria’s agreement is close to being finalised, while Queensland is yet to sign on.

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Butler this month said any changes would be through a process of co-design, and stressed all states and territories had agreed to a “package deal” of increased hospital funding in exchange for NDIS reforms.

Flagging major cuts to the budget, Chalmers said he would brief state treasurers, not disability ministers, on Tuesday.

“The NDIS is growing too fast for Australians to afford,” the treasurer said on Monday.

“This has been a really big part of our pre-budget deliberations. It is easily the most important part of the savings package that we will present on budget night.