The federal government has been told the timetable for rolling out the National Disability Insurance Scheme (NDIS) needs to be reassessed.
An independent review of the NDIS agency warns that including 300,000 people in the landmark scheme from 2017-2018 is a massive task that would put pressures on the organisation and available workforce in the disability sector.
"A realistic reassessment of these plans should be done soon rather than later," the review's expert panel said.
The panel was also critical of the Gillard government's decision to rush the scheme into operation, a year ahead of the date recommended by the Productivity Commission.
As well the decision to move the agency's headquarters to Geelong from Canberra diverted valuable resources.
"The agency is like a plane that took off before it had been fully built and is being completed while it is in the air," the panel said in a report released by the government on Thursday.
It described as "very, very difficult" the agency's timetable to meet a challenging role, warning any pressure to move faster may compromise its ability to successfully roll out the scheme.
"The focus should be on quality not time," it said.
Assistant Social Services Minister Mitch Fifield said the review's findings were both inspiring and sobering.
"Inspiring, because several thousand Australians with disability are now getting the better deal they deserve," he said in a statement.
Senator Fifield praised the "herculean" effort of agency staff in rolling out the scheme to trial states since July 2013.
The sobering aspect related to the impact the rushed start had on the agency's key capabilities to deliver a full roll-out of the scheme.
The review is likely to provide the government with ammunition to revise the roll-out timetable, a move previously flagged by Senator Fifield.
Labor accused Senator Fifield of making "outrageous and irresponsible" claims when he deliberately misrepresented numbers in the agency's second quarterly report in February.
It called on Prime Minister Tony Abbott to tell the minister to get on with the job of rolling out the scheme.