Funding for the NDIS won’t be reduced, the prime minister insists, despite concern from state and territory leaders that changes to the scheme will leave people with a disability worse off.

Laws before federal parliament aim to contain budget blowouts of the NDIS by limiting spending growth to eight per cent, as well requiring those on the scheme to complete needs-based assessments.

Under the changes, which came following a review of the scheme, money allocated to participants can only be spent in accordance with NDIS plans unless needs “significantly change”, while a list of services included in funding will also be created.

In a submission to a federal inquiry examining the proposed changes, premiers and chief ministers said they were worried those with disabilities might not get adequate support.

“Sates and territories share significant concerns with the provision of the (proposed laws) and the potential impacts on people with disability,” the submission said.

“We are genuinely worried that this bill undermines the vision of the NDIS review.”

Prime Minister Anthony Albanese said talks were under way with state and territory governments on the changes, but indicated capping funding growth would not mean a cut in services.

“The NDIS needs to be made sustainable. What we’re talking about here isn’t something that’s any reduction, it is a lowering of the projected increase in NDIS funding, which would see it unsustainable,” he told reporters in Sydney on Tuesday.

“We want to make sure that everyone with a disability gets the support that they need so they can fully participate in Australian society. That’s the objective of the NDIS.”

The cost of the NDIS has been predicted to surge to $50 billion by 2025/26, higher than the annual bill for Medicare.

Treasurer Jim Chalmers said the changes would ensure the NDIS would be the best version of the scheme it could be.

“We’re engaged with the states and territories on making sure that the NDIS can deliver for the people it was designed to serve,” he said.

“Funding for the NDIS will continue to grow. It will actually continue to grow quite strongly.

“But everyone – state and federal, everyone associated with the scheme – has an interest in and has a responsibility to make sure that we’re getting value for money.”

The NDIS changes will be put under the microscope at a parliamentary hearing later on Tuesday, with one of the program’s architects, Bruce Bonyhady, to give evidence.

– AAP