Colin Barnett has warned of a funding black hole in the $22 billion National Disability Insurance Scheme and the risk of it being exploited by profit-focused corporates.

The Premier said Australia’s political leaders were “being a bit cute” about the full cost of the insurance scheme.

He said the blowout was “way beyond what’s being talked about” and preparation for the full NDIS rollout was “progressing fairly slowly”.

“We know enough to know the final cost has blown out and that’s because of people using the service, the cost of delivery,” Mr Barnett said. “We don’t know exactly but it’s not marginal.”

A spokeswoman for Federal Social Services Minister Christian Porter denied there had been a budget blowout.

But she confirmed the rollout of the full NDIS would be delayed in WA, despite it beginning in all other States and Territories in July.

After former disability services minister Helen Morton’s exit from State Cabinet last week, Mr Barnett said there would be no change of direction from the State Government on the NDIS.

He still wanted WA to administer delivery of its disability services, rather than outsourcing them to the National Disability Insurance Agency in Geelong like the other States.

Noting that the not-for-profit sector had run WA’s disability services for the past 25 years, he cautioned other States they were going into “uncharted waters”.

Mission-focused not-for-profit organisations received much of WA’s disability funding to deliver services, but the NDIS opened it up to for-profit service providers.

“You will get full-profit organisations coming in, seeking a huge business opportunity and they may be very, very good but that’s not consistent with the way in which it’s developed,” Mr Barnett said.

Mr Porter’s spokeswoman said estimates were that about 460,000 people would be eligible for the NDIS at a cost of about $22 billion in 2019-20. She said the scheme would be rolled out using a “carefully managed, staged approach” to ensure the best outcomes for people with a disability and their families.

The future rollout of the NDIS in WA would be informed by the outcomes of the independent comparative evaluation of two trials in WA — the State Government’s My Way model in the Lower South West, Cockburn and Kwinana, and the Federal Government’s NDIA-run model in the Perth Hills — due to be completed in August.

This article first appeared on ‘The West Australian’ on 5 April 2016.