To be eligible for NDIS support, individuals generally need to meet the following criteria:
Age:

You generally need to be under 65 years of age when you first apply.1

Residency:

You must be an Australian citizen, a permanent resident, or hold a Protected Special Category Visa.2

Disability Requirements:

You must have a permanent and significant disability that affects your ability to participate in everyday activities.3
This means your disability:

Is likely to be permanent.
Significantly impacts your functional capacity.
Requires ongoing support.

Early Intervention Requirements:

In some cases, individuals may be eligible for early intervention support if they have a disability that is likely to be permanent, and early intervention can reduce the impact of the disability.4

Here are some key points to remember:
The NDIS focuses on providing support for people with permanent and significant disabilities.5
The NDIS also provides early intervention support to help people with disabilities and developmental delays.6
It is important to check the official NDIS website, as that will always have the most up to date information.
To get the most accurate and detailed information, I recommend visiting the official NDIS website:
ndis.gov.au7