Former chairman of the National Disability Insurance Scheme (NDIS) Bruce Bonyhady has labelled changes to the support scheme a "disgrace" that should be abandoned immediately before they cause more needless distress.

Mr Bonyhady made the remarks at a parliamentary inquiry into major reforms of the NDIS on Friday, calling proposed independent assessments "robo-planning" that would "fundamentally damage" the scheme.

He was the first witness at a one-day hearing in Melbourne being conducted by the Joint Standing Committee on the NDIS.

"It is not just current participants and their families who should be anxious and angry about what the government and the NDIA have planned," Mr Bonyhady told the inquiry.

"All Australians should be gravely concerned about robo-planning because it will tear up the social contract at the heart of the NDIS."