Canberra's peak provider for people with autism has been left in the dark about proposed dramatic changes to the National Disability Insurance Scheme.
One Canberra father said the flagged changes would be devastating.
Marymead chief executive Camila Rowland said she was "deeply concerned" about potential changes to the NDIS revealed last week.
The changes were previously flagged by the Productivity Commission and would limit the availability of services for people with less than severe autism.
Ms Rowland was only made aware of the possible overhaul after being contacted by the Sunday Canberra Times, despite reports the National Disability Insurance Agency had contacted key stakeholders nationally.
"We 're the main autism centre for the region," Ms Rowland said.
"We have 2000 people in our [autism centre's] client database."
Canberra father John Donovan, who himself has autism, cares for his two sons, Cameron, 16 and Nicholas, 20, who also have autism.
People with autism wouldn't be barred from care under the changes but may not be automatically eligible for support.
The levels range from one to three - mild to severe - under the Diagnostic and Statistical Manual of Mental Disorders V with the NDIA flagging removing level two people from List A which grants them automatic eligibility.
Mr Donovan's sons have been diagnosed as severe and moderate respectively under the previous DSM-IV scheme but he estimated Cameron was at level three, potentially level two, while he estimated Nick was at level two.
"Fighting to get the services for my children is very taxing and I have to put my own needs on the backburner," Mr Donovan said.
The changes wouldn't bar people with level two autism receiving List A support but would move them to List B which required independent assessment by the NDIA.
Marymead's Ms Rowland said the severity of a persons autism isn't always clear from a young age and they needed strong support and early intervention.
"Given that there have been widespread reports of inconsistencies in NDIA assessments, reviews and determinations, it is of concern that an independent professional diagnosis using the DSM-5 tool would be overlooked by the NDIA in preference for their own ‘in house’ alternative," Ms Rowland said.
"As NDIS operates on an insurance model, it would be expected that comprehensive early intervention funding packages would enable reduced cost to the NDIA over time."
"Any type of reduction in NDIS funding for these people, these individuals and families would be of a major concern to us."
Mr Donovan said the public servants at the NDIA were "out of touch".
"The public service is not a medical community. They need to take into account medical professions reports, not just a government cap," Mr Donovan said.
"What [Cameron] needs and what the NDIS is prepared to fund are two different kettles of fish."