What "Reasonable and Necessary" Actually Means Under the NDIS

What the reasonable and necessary test actually is

"Reasonable and necessary" — it's the phrase that governs every single dollar of NDIS funding. Section 34 of the National Disability Insurance Scheme Act 2013 sets out the legal test. If a support doesn't pass it, the NDIS won't fund it — no matter how much it might help.

Across a $40 billion+ scheme covering 650,000+ participants, this test is the gatekeeper. Understanding it — and learning to frame your requests through its lens — might be the single most useful skill any participant can develop. If you're preparing for your planning meeting, our NDIS planning meeting guide shows how to use these criteria to argue for the supports you need.

The six criteria every support has to meet

For a support to be funded, it has to pass all six of these:

1. The support must be related to your disability

Straightforward for some things (a wheelchair for someone who can't walk) and trickier for others (a gym membership for someone with a psychosocial disability — is that disability-related or general health?). The support has to directly address the functional impact of your impairment, not just improve your general wellbeing.

2. The support must not be day-to-day living costs

The NDIS doesn't pay your rent, groceries, or utility bills — those are expenses everyone has. But it will fund the extra costs your disability creates: the additional electricity to run a ventilator, or having meals prepared by a support worker because you can't cook safely.

3. The support must represent value for money

The NDIA weighs the cost against the benefit and against alternative ways to achieve the same outcome. A $5,000 custom piece of equipment might be funded instead of a $20,000 one with unnecessary bells and whistles. The NDIA doesn't have to fund the "best" option — just the one that gets the job done at a reasonable cost.

4. The support must be effective and beneficial

There needs to be evidence the support actually helps. For established therapies like physio and OT, this rarely gets questioned. For emerging or alternative therapies, the NDIA may want stronger proof. Anecdotal stories alone usually won't cut it.

5. The support must take into account informal supports

The NDIA looks at what family, friends, and community can reasonably provide. If your partner helps you shower every morning, the NDIA won't fund a support worker for that — unless the arrangement is unsustainable or it's unreasonable to expect your partner to keep doing it. This is where a lot of disputes happen: the NDIA often overestimates what family can provide long-term.

6. The support must be most appropriately funded by the NDIS

If another government system is responsible — Medicare, the education system, state health, disability programs — the NDIS won't pay. For example, the NDIS won't fund a teacher's aide at school (that's the education department's job), but it might fund therapy that helps a child participate in school.

Real examples: what gets funded and what doesn't

Gardening service

• Fails. Mowing the lawn is a day-to-day living cost (criterion 2), not disability-specific. The NDIS won't fund it — even if your disability stops you from doing it yourself.

Support worker for community access

• Passes. If your disability means you can't leave home alone safely, a support worker to go with you to community activities is related to your disability (criterion 1), effective (criterion 4), and not something family can reasonably provide every single time (criterion 5). Funded.

iPad for communication

• Passes — with caveats. For someone with a speech impairment using it as a communication device, it passes all six criteria. For someone who just wants an iPad for entertainment, it fails criterion 1 (not disability-related) and criterion 4 (no evidence of benefit for the disability). The NDIA funds the device when it's prescribed as assistive technology by an allied health professional.

Holiday travel

• Fails — mostly. A holiday itself is a day-to-day living cost. But the extra disability-related costs of a holiday — like extra support worker hours while travelling — can be funded if the holiday supports your goals (say "maintaining social connections by visiting family interstate"). Flights and accommodation? No. The support worker to make the trip possible? Possibly yes.

How to argue your support is reasonable and necessary

When you're requesting funding — in a planning meeting, a review, or an appeal — structure your argument around the six criteria. Here's a template that works:

1. Name the support — what are you asking for, specifically?
2. State your goal — which goal in your plan does this support help you reach?
3. Walk through the criteria — for each of the six, explain why this support passes. Use the language: "This support is related to my disability because…" "It represents value for money because…"
4. Provide evidence — a letter from your OT, physio, or specialist saying the support is necessary carries enormous weight. The NDIA almost never overrides a treating professional's recommendation without strong counter-evidence.
5. Address alternatives — anticipate the NDIA's objections. What's the cheaper alternative and why isn't it suitable? Why can't informal supports fill this gap? Head off the pushback before it arrives.

What the tribunal has said about reasonable and necessary

The Administrative Appeals Tribunal (AAT) — now replaced by the Administrative Review Tribunal (ART) for NDIS matters — has issued dozens of decisions interpreting "reasonable and necessary." Some key principles that keep coming up:

• "Reasonable" doesn't mean "cheapest." The AAT has repeatedly found the NDIA must fund supports that are effective, even if cheaper options exist — as long as the cost isn't wildly disproportionate to the benefit.
• Informal supports must be sustainable. The AAT has pushed back against the NDIA's habit of assuming family can provide unlimited support forever. Carer burnout and ageing parents are legitimate reasons to increase formal supports.
• Early intervention is taken seriously. The AAT has upheld funding for supports that prevent deterioration, even when the immediate benefit is hard to measure, because the long-term cost of deterioration is higher.

If the NDIA denies your request and the denial contradicts AAT precedent, you have strong grounds for review. Knowing what's been decided before is some of the best evidence you can have. For the full process of challenging NDIA decisions, read our NDIS complaints and appeals guide.