Reasonable and Necessary, in Plain English

What the phrase actually means

Reasonable and necessary is not a mood or a judgement about how deserving you are. It is a set of criteria in the NDIS Act that every funding decision is tested against, and a support has to satisfy all of them, not most of them.

That matters practically. If a request is knocked back, it usually failed one specific criterion rather than being rejected in general, and the fix is to answer that one. Most people argue harder on the criterion they already passed.

The six questions a delegate is asking

Does it relate to your disability? The support has to connect to the impairment that got you into the scheme, not to something else going on in your life. A cleaner because you find housework difficult due to your disability is a different case from a cleaner because you are busy.

Is it a day-to-day living cost everyone has? Rent, food, power and phone bills are not funded, because everyone pays them. The NDIS funds the extra cost that disability adds, not the ordinary cost of living. Our piece on what SIL funding does not pay for works through where that line sits in a supported home.

Is it value for money? Not cheapest. Value compared to the alternatives, including what it prevents. A home modification that costs a lot once can be better value than years of daily support hours doing the same job.

Is it likely to be effective and beneficial? This is where evidence does the heavy lifting. It asks whether the support actually works, judged against good practice, so an assessment from a relevant professional carries more weight than a preference.

Does it account for informal supports? What family, friends and the community already do is taken into account. This one is worth understanding rather than resenting, because a delegate can only account for what they know about.

Is it the NDIS that should fund it? Health, education, housing and justice systems have their own responsibilities. A support that belongs to the health system is not funded by the NDIS even when it is plainly needed.

The criterion that trips people up most

Informal supports. Families often describe everything they do, in detail, as evidence of how high the need is. It can read the other way: as proof the need is already met.

The honest framing is about sustainability rather than heroics. What are you doing now, what is it costing you, and what happens when it stops. A parent in their seventies doing two transfers a night is not a stable arrangement, and saying so plainly is more useful than describing how well they cope.

Say what you would like to change, too. Informal support is meant to be what a family reasonably provides, not everything a family is physically capable of providing.

What evidence answers which question

Match the document to the criterion and a lot of frustration disappears.

For the disability link and for effectiveness, you want a report from someone qualified in the relevant area, naming the impairment, the functional impact and the recommended support with a frequency. For value for money, a comparison helps: this option, that option, what each costs and what each avoids.

For informal supports, a plain description from the family of what is being provided now and what is not sustainable. For the wrong-system question, sometimes a letter from the other service saying it is not their responsibility is the single document that changes the answer.

Our guide to writing evidence a planner can use covers the shape of a report that answers these questions rather than describing a person in general terms.

What it does not mean

It does not mean cheapest, and a delegate is not required to fund the lowest quote if it would not work.

It does not mean you have to prove you are worse off than someone else. There is no queue and no comparison against other participants.

And it does not mean a decision is final. There are internal review rights and timeframes, and a decision that turned on missing evidence often changes when the evidence arrives. Decisions sit with the NDIA and turn on what is in front of them, so nobody, including us, can tell you what the outcome will be.

If a support has been refused, ask which criterion it failed. You are entitled to reasons, and the answer tells you exactly what the next piece of paper needs to say.

Before your next planning conversation

Write each support you want to ask for on its own line, and beside it write the criterion you think a delegate will query. Then find the document that answers that one.

It is slow the first time and quick after that, because the same handful of documents answer most requests. Our piece on what a reassessment actually needs covers assembling that file.

Frequently asked questions

Who decides what is reasonable and necessary?

An NDIA delegate makes the decision, applying the criteria in the NDIS Act to the information in front of them. A therapist can recommend a support and a provider can describe what it involves, but neither can approve it. That is why written evidence matters more than a persuasive conversation: the delegate deciding may never have met you.

Does a therapist recommending a support mean it gets funded?

No, though a well written recommendation is usually the strongest single piece of evidence. It has to connect the support to your disability, explain why it is likely to be effective, and ideally address value compared with alternatives. A recommendation that simply names a service without that reasoning often does not carry the request.

What counts as an informal support?

Help that is not paid for: family, friends, neighbours, and community connections. The NDIS takes into account what is reasonably available rather than everything that is theoretically possible, so it is legitimate to say that an arrangement is not sustainable, or that a family member wants to return to being a parent or a partner rather than a carer.

Can I ask why a support was refused?

Yes. You can ask for the reasons for a decision, and knowing which criterion it failed is what makes a further request worth making. If you disagree, there are internal review rights with set timeframes. Check the current process on the NDIS website rather than relying on what applied under a previous plan.