As an assembly inquiry heard the harrowing stories of those left behind by the scheme, the Barr government revealed it will pledge $1.8 million in next month's budget to support people with high or complex support needs not "currently being met" by the NDIS.

That will include those in crisis requiring emergency funding for services, as well as those in particularly complex or vulnerable positions. It is understood funds will be allocated on a case-by-case basis and paid directly to service providers on behalf of participants, without going through the NDIS.

Like other states and territories across Australia, the ACT pulled out of the disability sector as the NDIS rolled into town, leaving the capital without a provider of last resort.

At least one child with high needs had been relinquished to the ACT in that time, the parliamentary inquiry heard this month, as their family could not longer care for them, while others had been hospitalised by the stress of navigating the scheme.

Craig Wallace at the ACT Council of Social Services said a number of people were now "close to breaking point". He welcomed the new funding hit, which includes $400,000 for independent advocacy to help people navigate the NDIS.

"It can be a real David and Goliath struggle for people," Mr Wallace said.

ACT Minister for Disability Rachel Stephen-Smith said the territory was proud to be the first jurisdiction in Australia to roll-out the NDIS, but said the new support money came in response to challenges faced by some local participants.

"This transition to an entirely new service model is complex and the ACT government is committed to ensuring that no-one seeking support gets left behind," she said.

The ACT Office of Disability would also get more staff to help it track problems on the ground and coordinate directly with participants as well as the National Disability Insurance Agency, which manages the scheme.

This month, participants, service providers and advocates told the parliamentary inquiry that the well-intentioned national reform had become bogged down in an increasingly opaque bureaucracy.

People were routinely left in limbo waiting for funding, others had missed out entirely on vital supports and therapies.

Mr Wallace said many of the problems raised before the inquiry had been known for a number of years, and it was never the intention of the scheme to replace mainstream supports for people with disability.

"It's a misnomer that the [NDIS] would simply come in and all of a sudden the ACT would have no stake in disability services anymore," he said.

"We've been saying the ACT needed to ensure continuity of support...we've said it across a number of budget cycles."

On Thursday, Mr Wallace called on both the Commonwealth government and the agency to "step up" its response to problems with the scheme.

"We've heard some harrowing concerns at the inquiry...but we have yet to see signs that the agency is seized of the need for change in the same way that the ACT seems to be."