The National Disability Insurance Scheme (NDIS), which supports some of the nation's most vulnerable people, is plagued with serious delays and is frustratingly difficult to understand, according to a review.

Key points: A recommendation of the report was to extend the life of funding support for recipients from two to three years if their needs are "stable"

A recommendation of the report was to extend the life of funding support for recipients from two to three years if their needs are "stable" People with disability reported poor experiences when working with NDIA staff

People with disability reported poor experiences when working with NDIA staff Other recommendations include calls for more flexibility for how NDIS funds are used by recipients and measures to make funding plans easier to understand

The NDIS was heralded as a landmark program for Australians with a disability when it was established in 2013, but it has long been criticised as being bogged down in red tape and bureaucracy.

After the election in May 2019, the Federal Government commissioned former senior public servant David Tune to review the NDIS and the way it is managed by the National Disability Insurance Agency (NDIA).

His report has now been released publicly and includes 29 recommendations on how to improve the program — including extending the life of funding support for recipients from two to three years if their needs are "stable".

"People with disability have reported frustrations about the administration of the NDIS by the NDIA," the report stated.

"Transparency, consistency and timeliness in decision-making are critical issues and people with disability have reported poor experiences when working with NDIA staff.

"It will still take a number of years before the NDIS is delivering consistent, positive experiences for people with disability."

The report noted the timeframe for rolling out the NDIS was "ambitious", and said the next few years would give the NDIA an opportunity to fix some problems.

The 29 recommendations include calls for more flexibility for how NDIS funds are used by recipients, measures to make funding plans easier to understand, and putting in place a "participant service guarantee" to ensure basic standards are met.

"It is reasonable to expect that there will always be some gap between participants' expectations of the NDIA and the reality of what the NDIA will be able to provide," the report said.

"The NDIA should aim to reduce this gap as much as possible."

The Federal Government said it would formally respond the report in coming weeks, but it had already promised to implement longer funding plans for recipients.

"The review's findings reaffirmed what we have been hearing from participants, their families and carers and the disability sector," NDIS Minister Stuart Robert said in a statement.

"While many participants have had excellent experiences and are benefitting from the scheme, many others have had frustrations with wait times, complexity of processes and a lack of understanding of their needs.

"We'll use these findings to update and clarify the legislation and remove barriers to a better NDIS."