The state's chief mental health group has seized upon a report which shows the National Disability Insurance Scheme is failing a high proportion of people with serious mental illnesses.
Community Mental Health Australia and the University of Sydney recently released the report on the scheme which showed slow progress on the transition of people from mental health programs to the NDIS.
It showed a high number of people had either not applied to be part of the scheme, or had applied and been found ineligible.
Mental Health Council of Tasmania chief executive Connie Digolis said the data showed there may be inadequate supports in place for people with serious mental illnesses by June next year.
"We could see their mental health declining as a result rather than having access to the care they need," she said.
"This is an unacceptable outcome for some of the most vulnerable in our community."
Report author Nicola Hancock said the data suggested those with mental illness who did not apply for the NDIS were most in need of support.
"For many, it is the severity of their mental illness that is precluding them from engaging in the complex and stressful process required to apply," she said.
A National Disability Insurance Agency spokesperson said the organisation had worked closely with Community Mental Health Australia and other mental health stakeholders to improve access processes to the scheme for people with a psychosocial disability.
They said the agency had also worked to improve links to support for those found to be ineligible to partake in the scheme.
"The NDIA has streamlined its access processes for people who wish to apply for the NDIS," the spokesperson said.
"As at 30 June, 25,192 participants with psychosocial disability had benefited from the NDIS.
"This number represents an 87-per-cent increase on the same time last year, demonstrating the scheme is offering supports to increasing numbers of people with psychosocial disability."