NDIS Reasonable and Necessary Criteria Explained in Plain English

What reasonable and necessary actually means

The phrase “reasonable and necessary” describes the legal test the NDIA applies when deciding what supports to fund in a participant’s plan. It is not a vague judgement call made on the day. It is a specific set of criteria set out in the NDIS Act and rules, and a planner has to consider each one when making a funding decision.

This matters practically because two participants with a similar diagnosis can end up with quite different plans, because the test looks at individual circumstances, goals and evidence rather than applying a flat rule based on a condition alone. A support that is reasonable and necessary for one participant may not be for another, depending on their specific situation.

Understanding the test helps participants and families present information in a way that actually engages with how the decision is made, rather than simply describing a diagnosis and hoping funding follows automatically.

The reasonable and necessary criteria explained

Several specific questions sit behind the general phrase, and a support generally needs to satisfy all of them together, not just one.

• Related to the disability: the support must connect to the participant’s disability, not be a general lifestyle preference unrelated to their support needs.
• Not day-to-day living costs: ordinary costs such as rent, groceries or utilities are not funded, even where the participant has a disability.
• Value for money: the cost of the support should be reasonable relative to its benefit and alternative ways of achieving the same outcome.
• Likely to be effective: there should be a reasonable basis to expect the support will actually help, based on good evidence or practice.
• Takes into account other supports: the NDIA considers what is already reasonably provided by family, carers, the community, or other government services such as health and education.

How the whole plan is assessed, not just single items

It is easy to think of each support as being tested in isolation, but the NDIA also considers the plan as a package. A combination of supports needs to make sense together and represent a reasonable overall response to the participant’s circumstances, not just a list of individually justifiable items.

This is one reason a plan can look quite different between two people with similar individual needs, since the overall mix, not just each line item, is what gets assessed for reasonableness as a whole.

What tends to be excluded

A few categories come up repeatedly as excluded or difficult to fund, and understanding them early avoids wasted effort during a planning meeting.

• General living costs such as rent, groceries, or utility bills, even where a disability makes budgeting harder.
• Supports that duplicate what another government service, such as health or education, is already responsible for funding.
• Items or services with no reasonable evidence that they will actually help the participant achieve their goals.
• Costs that would be expected of any person, disabled or not, in similar life circumstances.

Building a stronger case for a support

A request is far more persuasive when it clearly walks through each part of the test, rather than simply asserting that a support is needed.

1. Describe the specific disability-related barrier the support addresses.
2. Explain why existing informal, community or mainstream supports are not already enough.
3. Provide evidence, such as a therapy report, that supports the likely effectiveness of the request.
4. Compare cost against reasonable alternatives, showing why this option represents value for money.
5. Connect the request back to a specific, stated goal in the participant’s plan.

Evidence that helps versus evidence that does not

Not all evidence carries the same weight. A one-line letter confirming a diagnosis rarely does much on its own, while a report explaining specific functional impact tends to be far more persuasive.

• Reports that describe specific tasks that are difficult and why, rather than only naming a condition.
• Evidence that links a requested support to a stated goal in the plan.
• Clear information about what has already been tried and why it was not enough.
• Cost comparisons, where relevant, showing the requested support is reasonable relative to alternatives.

Common mistakes when arguing for a support

• Relying on a diagnosis alone, without explaining the specific functional impact.
• Requesting a support that clearly overlaps with health, education or another mainstream service’s responsibility.
• Not addressing why family or informal supports cannot reasonably continue providing the same help.
• Ignoring cost and value for money entirely, even when a cheaper reasonable alternative exists.
• Treating the plan as a wish list rather than a connected package tied to specific goals.

What to do if a support is declined

If a requested support is not included in a plan, it is worth asking specifically which part of the reasonable and necessary test was not satisfied, rather than assuming the decision cannot be explained. This makes it much easier to address the actual gap rather than resubmitting the same request unchanged.

From there, participants can provide additional evidence, request an internal review, or ask a support coordinator to help reframe the request so it more directly engages with the specific criteria that were not met the first time.

What value for money actually means in practice

Value for money does not mean the cheapest possible option must always be chosen. It means the cost of a support should be reasonable when weighed against the benefit it provides and any comparable alternatives that could achieve a similar outcome. A more expensive option can still represent value for money if it clearly works better or lasts longer than a cheaper alternative.

In practice, this often means being ready to explain why a particular provider, piece of equipment or level of support was chosen over other reasonable options, rather than simply presenting a single quote with no comparison at all.

How informal and mainstream supports factor into the test

One of the more misunderstood parts of the criteria is how family, carers and mainstream services are weighed. The NDIA does not expect family members to provide unlimited unpaid support, but it does consider what informal support is already reasonably being provided, and whether it is sustainable long term.

This is why requests that acknowledge current informal support, and explain clearly why it cannot reasonably continue at the same level, tend to be better received than requests that ignore informal support altogether or simply assume the NDIS should replace it entirely.

Similarly, if a need clearly sits within the responsibility of the health or education system, such as a medical treatment or a classroom aide, the NDIA is likely to direct the participant back to that system rather than funding it directly, even where the participant also has an NDIS plan.

Applying the test to everyday funding requests

The reasonable and necessary test can feel abstract until it is applied to an actual request. For a request relating to community participation, for example, a planner will typically want to understand what specific barrier is being addressed, why existing informal or community options are not enough, and how the requested support connects to a stated goal such as building friendships or accessing local activities independently.

For a request relating to equipment or home modifications, the same test applies, but the evidence tends to lean more heavily on professional assessments, since these decisions often involve higher costs and longer-term commitments.

Example scenario

Consider a participant requesting funding for a specialised piece of equipment. Simply naming the equipment and the diagnosis is unlikely to be persuasive on its own. A stronger request explains the specific daily task the equipment addresses, references an occupational therapy assessment recommending it, and compares its cost against similar available options.

It also explains why existing supports, such as help from a family member, are not a sustainable long-term substitute, and connects the request directly to a stated independence goal in the plan.

This is a general illustration only. Every request depends on the participant’s own circumstances, evidence and goals.

Who actually makes the decision

An NDIA planner or delegate makes the final decision about what is included in a plan, weighing the evidence and information provided against the reasonable and necessary criteria set out in the NDIS Act and rules. This is a structured decision, not a subjective preference, which is part of why clear, specific evidence matters so much.

Support coordinators, allied health professionals and plan managers can all help present a case, but the decision itself sits with the NDIA, and it can always be revisited through a review process if the participant believes the criteria were not applied correctly.

How the criteria applies to assistive technology and equipment

Requests for assistive technology or equipment are assessed against the same reasonable and necessary criteria as other supports, with particular attention to whether the item relates to the participant’s disability and whether it represents value for money compared with alternative options.

Quotes, assessments from an occupational therapist or other relevant professional, and a clear explanation of how the item supports the participant’s goals all help demonstrate that a request meets the criteria.

Important terms to understand

Reasonable and necessary language often overlaps with other funding and planning terms, so understanding how they connect helps when preparing evidence.

How this applies locally

Participants in Canberra and Queanbeyan often draw on a mix of NDIS providers, health services and community organisations, which makes it especially important to be clear about which system is responsible for which part of a support request.

CCS helps participants prepare requests that clearly address the reasonable and necessary criteria, rather than assuming a diagnosis or general need will speak for itself.

Related CCS Guides and Services

• What Happens at an NDIS Plan Reassessment Meeting
• Core, Capacity Building and Capital Supports Explained
• How to Ask for NDIS Home and Living Supports: Evidence Checklist for 2026
• NDIS Supports List and Replacement Supports: A Plain-English Guide
• Support coordination in Canberra
• Contact CCS

Official NDIS References

• What is reasonable and necessary
• Guide to NDIS support budgets

Frequently Asked Questions