The ACT government and disability advocates hope the appointment of a new federal minister to oversee the $22 billion scheme might prompt an 11^th hour backdown on planned changes, in particular the introduction of so-called independent assessments.

ACT Disabilities Minister Emma Davidson said the changes threatened to undermine the core principal that NDIS participants had "choice and control" over the support they received.

In a letter to former NDIS Minister Stuart Robert and National Disability Insurance Agency boss Martin Hoffman, Ms Davidson also accused the federal government of increasingly "acting unilaterally" in pursuing major changes.

Demoted as defence minister in a reshuffle sparked by federal parliament's culture crisis, Linda Reynolds has replaced Mr Robert in the NDIS portfolio amid escalating opposition to reforms developed under his watch.

Much of the concern has centred on the introduction of a new independent assessment process for participants, which Mr Robert announced last year in response to David Tune's review of the scheme.

Under the existing regime, people wanting to enter the scheme present reports and assessments from their own doctors, physiotherapists and other experts to the NDIA to help it determine their eligibility.

But under a new process set to be brought in later this year, government-appointed firms would be used to conduct mandatory assessments.

Existing participants would be subjected to independent assessments at certain checkpoints, such as when they started school or work, or requested a review of their plan.

Mr Robert has argued the new model would be fairer and result in more consistent assessments.

Announcing the changes last year, he said all Australians with a significant and permanent disability deserved "objective and unbiased" access to NDIS supports - not "just those who can pay the most for a report".

First trialled in 2018, the decision to use independent assessments on permanent basis triggered a fierce backlash from disability groups.

A coalition of Canberra-based disability groups last month wrote to Ms Davidson, highlighting their deep concern about the changes and imploring the ACT to lobby the federal government to put them on hold.

Among the groups' concerns was the potential for trauma to be inflicted on participants by forcing them to undergo assessments by professionals they didn't know.

"To require a person with disability to be observed by someone who is not known to or chosen by them, in order to justify their support needs, does not align with the principle of dignity of the individual," the letter read.

Ms Davidson wrote to Mr Robert and Mr Hoffman on March 9 to raise concerns about the new system, and the government's handling of its implementation.

The strongly-worded letter, which The Sunday Canberra Times has seen, was sent after the NDIA had announced the eight providers picked to run the independent assessments.

Ms Davidson noted the announcement was made just two days after consultation on the new system had closed. According to the letter, it also came despite an agreement further consultation would be undertaken, after state disability ministers raised "significant concerns" about the rollout at recent meetings.

At least two other state disability ministers - Labor's Luke Donnellan in Victoria and Liberal Gareth Ward in NSW - have in recent days called for more consultation.

"The announcement of the panel in the ACT will add to, rather than, allay concerns; including that the introduction of independent assessments is a cost-cutting exercise by the Australian government," Ms Davidson said in the letter.

The views of Ms Davidson and her interstate counterparts are significant, given the states and territories jointly fund the scheme with the Commonwealth.

Ms Davidson said in the letter she had become somewhat concerned the federal government was "increasingly acting unilaterally on matters relating to the NDIS", including decisions on the principal of choice and control and the scope of "reasonable and necessary supports".

In an interview with The Sunday Canberra Times, Ms Davidson said the appointment of Senator Reynolds presented an opportunity to halt the proposal as it stands and start a new "co-design" process with the disability community.

"I'm really wanting us to go back to the original intent of the NDIS and be true to that ... about people with a disability having choice and control over their lives and having continuity of care," she said.

Disability advocate Craig Wallace said Senator Reynolds' appointment should be used as a "reset" to the reforms, which he argued were "well-intentioned in their framing" but were now clearly "problematic for all kinds of reasons".

He urged the new minister to immediately take the "worst things off the table", including the intrusive aspects of the independent assessments which he said were at odds with the spirit of the NDIS.

"It is just absurd that people with a disability should be asked about their intimate lives and sex lives in order to be able to get funding for wheels on a wheelchair," he said.

Canberra Labor MP Alicia Payne, who sits on parliament's NDIS committee, said she had been inundated with feedback about the issue in recent weeks, including from participants who feared they would be stripped of supports they'd fought to access once the new assessment process was introduced.

"It's clear to me that it's the government's approach ... which is about cost-cutting," she said.

"It's not about trusting people with disabilities that they know what is best for them. Choice and control is supposed to be the guiding principal of the NDIS."

In a statement to The Canberra Times, an NDIA spokesman confirmed the government was pressing ahead with the reforms.

Proposed legislation was due to be unveiled "shortly", the spokesman said, with a view to it passing parliament and the changes coming into effect by mid-year.

A set of draft laws leaked last month to the media indicated the government was considering sweeping changes beyond the use of independent assessments, including denying funding to people with acquired brain injuries and fetal alcohol spectrum disorder.

The government reportedly canvassed the possibility of removing the "reasonable and necessary" test for the provision of support and services - but Mr Robert had since ruled that out.

The NDIA spokesman said it had been in ongoing consultation with peak bodies, participants and their families for the past two years about the design and delivery of independent assessments.

Since Mr Robert announced the plan last year, the spokesman said the agency had run a second trial and published a consultation paper which received more than 700 submissions.

"Independent assessments are being introduced to ensure all eligible Australians with disability are supported to apply for the NDIS, irrespective of their circumstances, by providing free individual assessments completed by health care professionals," he said.

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