What is Reasonable and necessary?
“Reasonable and necessary” is the statutory test the NDIA applies when deciding whether to fund a support. The support must relate to the participant’s disability, represent value for money, be likely to be effective and beneficial, take account of informal supports, and not be the responsibility of another service system such as health or education.
The test comes from section 34 of the NDIS Act. Every funding decision, and every dispute about one, turns on it.
For providers, the practical consequence is evidentiary: a support is easier to justify at plan review when progress notes actually show what was delivered and what changed. Notes written as a compliance chore rather than a record of outcomes are the reason plans get cut.
The criteria in section 34
Section 34 of the NDIS Act 2013 sets the criteria. Before funding a support, the NDIA must be satisfied that:
- it is related to the participant's disability
- it will help them pursue the goals in their plan
- it will help their social and economic participation
- it represents value for money compared with the costs and benefits of alternatives
- it will be, or is likely to be, effective and beneficial, having regard to current good practice
- it takes account of what is reasonable to expect families, carers, informal networks and the community to provide
- it is an NDIS support for the participant.
Each support and the whole package
Every support must meet all the criteria on its own, and the supports must also be reasonable and necessary as a package. A support must also be an NDIS support under section 10 of the Act, and it must not be a type of support the law says cannot be funded.
What the NDIA weighs up
- Value for money: the NDIA looks at costs and benefits, including whether a support reduces the need for others. Funding a vehicle modification, for example, may reduce the support needed to access the community.
- Effective and beneficial: the NDIA considers evidence that the support works for people with similar needs, and the participant's lived experience. It will not need an expert report for every support.
- Informal supports: the NDIA will not fund support it would reasonably expect family, friends or the community to provide.
Writing reports that meet the test
- Link each recommended support to the participant's disability and to a goal in their plan.
- Explain the evidence that the support is likely to work.
- Compare it with alternatives and show the cost difference.
- Describe what informal supports are available and where they stop.
Questions people ask
Where is reasonable and necessary defined?
In section 34 of the National Disability Insurance Scheme Act 2013, which lists the criteria every funded support must meet.
Who decides if a support is reasonable and necessary?
The NDIA decides when it creates or changes a participant's plan. NDIS partners and providers can supply evidence but cannot make the decision.
Does the NDIA need an expert report for every support?
No. It can often rely on other information, such as whether the support is widely accepted for people with similar needs.
Can the NDIA refuse a support because family would usually provide it?
Yes. The NDIA must take account of what it is reasonable to expect families, carers, informal networks and the community to provide.
Checked against the official sources on 2 October 2026. Rules change: confirm the current position with the agency before you rely on it.
Related terms
Rostery handles this in practice
SCHADS interpretation, NDIS price-guide validation, claiming and the evidence an audit asks for — built for Australian providers.