There are two types of rehabilitation referrals.
The first type, the full rehabilitation assessment is required for the majority of clients.
However the second, a specific service assessment, may be an 'add-on' if appropriate for the client at the time, or as a separate and 'one-off' activity.
Links
[1] https://clik.dva.gov.au/user/login?destination=comment/reply/21032%23comment-form