"Reasonable and necessary" — the legal test, explained

When the NDIA decides whether to fund a support — a therapy, a piece of assistive technology, a hoist in your bathroom, a support worker — they apply a single legal test. Six criteria. All six must be satisfied. This test is called 'reasonable and necessary' and it comes from section 34 of the NDIS Act. It is, in practice, the only thing the delegate is doing when they look at your plan.

The six criteria

1. 1The support will assist the participant to pursue the goals, objectives and aspirations in their plan.
2. 2The support will help the participant to undertake activities that enable them to participate in social and economic life.
3. 3The support represents value for money — meaning the cost is reasonable relative to the benefit, and to the cost of alternative supports.
4. 4The support will be, or is likely to be, effective and beneficial for the participant, having regard to current good practice.
5. 5The funding of the support takes into account what it is reasonable to expect families, carers, informal networks and the community to provide.
6. 6The support is most appropriately funded through the NDIS — and is not more appropriately funded or provided through other general systems of service delivery (health, education, community services, justice).

Each of these six is a separate test. A support can pass the first four and still fail the fifth or sixth, and not be funded. This is why parents sometimes get 'no' on a support that is clearly evidence-based and clearly needed — the NDIA often fails it on criterion 6, 'more appropriately funded by another system'.

Walking through each criterion

Criterion 1 — Connects to a plan goal

Every funded support must link back to a goal in the plan. This is why the planning meeting matters so much — goals written too narrowly limit what can be funded. 'Alex will learn to communicate her needs without frustration' opens funding for speech, OT, psychology, and behaviour support. 'Alex will have weekly speech therapy' locks funding only to the specific support named.

Criterion 2 — Social and economic participation

The support must help the person participate in community, employment, education, family life — the things any Australian would expect. Supports that are purely about comfort, convenience, or adult preference don't qualify. A communication device? Yes. A tablet for general entertainment? No.

Criterion 3 — Value for money

Value for money doesn't mean 'cheapest'. It means the benefit is commensurate with the cost, including comparison to alternative supports that might achieve the same outcome. A $10,000 piece of assistive technology that replaces the need for a support worker is usually good value. The same $10,000 on intensive therapy that duplicates what schools already provide probably isn't.

Criterion 4 — Effective, evidence-based, current good practice

The support must be grounded in evidence. For autism, that includes speech pathology, OT, behaviour support, and psychology. It has, in recent NDIA decisions, explicitly excluded certain alternative therapies (hyperbaric oxygen, chelation, MMS, certain sensory diets that aren't supported by current evidence) — these are routinely knocked back under criterion 4.

Criterion 5 — Reasonable family/community contribution

The NDIA assumes families will do what an average Australian family would do for a child that age. Driving to appointments, packing lunches, supervising homework, managing daily routines — this is family responsibility, not NDIS responsibility. But supports that go beyond what a typical family would provide — specialised behaviour support that requires training, overnight respite for a child with complex medical needs, personal care that another child wouldn't need — those are fundable.

The argument in most applications is that while some support is family responsibility, this child's level of support is beyond that threshold. Evidence matters here.

Criterion 6 — NDIS, not another system

This is the criterion that trips up more families than any other. The question is: whose job is this, really? If the answer is 'Medicare' (e.g. medical treatment), 'schools' (e.g. educational support, reasonable adjustment), 'public mental health' (acute psychiatric care), 'child protection' (family support), or 'housing' — then NDIS won't fund it, no matter how much the child needs it.

We have a full chapter on the NDIS-vs-schools boundary because it is a constant source of dispute. The short version: the NDIS funds disability-specific supports that other systems don't cover. It does not duplicate or replace universal services.

Why knowing the test matters

When you request a support, you are implicitly arguing that all six criteria are met. When the NDIA says no, they are saying at least one criterion is not met. If you know which criterion is in dispute, you can target your evidence.

For example: your daughter's OT has recommended weighted blankets and a sensory swing ($1,100). The NDIA denies funding. Why? Usually one of:

• Criterion 3 — doesn't see the items as value for money.
• Criterion 4 — considers the evidence base for sensory equipment in this child's profile weak.
• Criterion 5 — considers this the sort of thing a family would normally buy.
• Criterion 6 — sees it as more appropriate to have schools or Medicare provide sensory-integration therapy instead.

Your appeal addresses whichever criterion is in dispute. A request letter that specifically responds to the criterion being invoked is far stronger than a general 'please reconsider'.

The things 'reasonable and necessary' usually covers

• Allied health therapy — speech, OT, physio, psychology, behaviour support.
• Assistive technology — communication devices, sensory equipment, specialised seating, wheelchairs.
• Home modifications — ramps, bathroom modifications, hoists (with specialist assessment).
• Personal care — support workers for feeding, dressing, toileting, beyond what's age-typical.
• Community access — support worker hours for participation in community activities.
• Transport — where mainstream transport is unsafe or inaccessible.
• Capacity building — therapy-assisted skill development, parent training, support coordination.
• Consumables — continence aids, specialised dietary supplements (where medically necessary).

The things 'reasonable and necessary' usually does not cover

• Medical treatment, including medications, GP visits, paediatric appointments, surgery. That's Medicare.
• School costs — tuition, uniforms, textbooks, excursions. That's the schools and the family.
• Private schooling or specialist school fees.
• Childcare and day care — except where additional support is needed for the disability itself.
• General household costs — food, clothing, general toys, family holidays.
• Rent or mortgage (except for some specialist disability accommodation scenarios).
• Private transport — a standard car, or most petrol costs.
• Therapies without an evidence base for the child's profile.