People with disabilities are facing delays of up to nine months when they attempt to have their bungled National Disability Insurance Scheme (NDIS) plans fixed, an investigation has found.

Key points: NDIS participants seek reviews when their plan does not fit with their needs, for example if they receive funding for fewer hours of care than needed

NDIS participants seek reviews when their plan does not fit with their needs, for example if they receive funding for fewer hours of care than needed Ombudsman's report found up to 8,000 people are still waiting for an outcome on their reviews

Ombudsman's report found up to 8,000 people are still waiting for an outcome on their reviews Agency accepted finding that it was not prioritising urgent cases, where people could be at risk of harm or homelessness

The Commonwealth Ombudsman's report into the NDIS's plan review system has revealed up to 8,000 people are stuck waiting for an outcome.

People seek reviews for many reasons, including when their plan includes wrong or inadequate equipment and support, for example if they receive funding for fewer hours of care than needed.

The Ombudsman described the review processes as "unwieldy", "unapproachable", and lacking "fairness and transparency".

"[Delays] pose a particular risk to those who may be at risk of losing services or experiencing deterioration in their capacity if their plan is not adjusted quickly," the report said.

"Some participants have told us they have been waiting for up to eight or nine months for a decision on their review request, without any update on its progress or explanation of the time taken."

The Ombudsman said it received 400 complaints about the National Disability Insurance Agency's (NDIA) review processes over the 18 months to January.

"In one case, a participant did not know why her plan was changed because the NDIA had not told her it had accepted (and given effect to) her request for a plan review," the report said.

Reports to the watchdog included:

The agency not prioritising urgent cases where, for example, people could be at risk of harm or homelessness

The agency not prioritising urgent cases where, for example, people could be at risk of harm or homelessness NDIA staff and contractors discouraging people from seeking a review

NDIA staff and contractors discouraging people from seeking a review The NDIA not acknowledging requests for review or responding to enquiries

More than 140,000 Australians are now covered by the NDIS — a number expected to reach 475,000 by early next decade.

The NDIA has accepted the Ombudsman's 20 recommendations.

"[The agency] has started determining the most practical way to implement responses," a spokesman said in a statement.

"The NDIA has established a dedicated team to manage outstanding reviews.

"The NDIS is a world-first reform, the size and scale of which means the scheme will not be without challenges."

Social Services Minister Dan Tehan reinforced the message that the NDIA was dealing with the issues outlined in the report.

"This was something that was identified some months ago and special teams have been put in place to address this issue," he said.

"Obviously when you undertake a reform of this scale there will always be issues that we need to work through … we're doing everything we can to speed up the process."

Federal Labor's social services spokeswoman Jenny Macklin said it was "an absolutely damning report".

"These problems need to be fixed, and fixed right now," Ms Macklin said.

"Get peoples' plans right the first time so we just don't need all these reviews done, and people waiting for much-needed support."