A terrorist organisation is an organisation that:

a court finds is directly or indirectly engaged in preparing, planning, assisting or fostering the doing of a terrorist act
or
the government has listed as a terrorist organisation by regulations.
Listing of terrorist organisations

The government can list an organisation as a terrorist organisation if the Attorney-General is satisfied that it:

is engaged in preparing, planning, assisting or fostering the doing of a terrorist act
or
advocates the doing of a terrorist act.
An organisation advocates the doing of a terrorist act if it directly or indirectly:

counsels, promotes, encourages or urges the doing of a terrorist act
gives instruction on the doing of a terrorist act
directly praises the doing of a terrorist act, where there is a substantial risk that this praise might lead someone to engage in a terrorist act.
The government can list an organisation for three years. The Attorney-General may also add or remove the name of an alias to a listed terrorist organisation. The Attorney‑General's decision to list an organisation as a terrorist organisation or add or remove the name of an alias is publicly reviewed by the Parliamentary Joint Committee on Intelligence and Security.

You will find listed terrorist organisations on the Australian National Security website.

Offences in relation to terrorist organisations

It is an offence to:

be a member of a terrorist organisation
direct the activities of one
recruit for one
train or receive training from, or participate in training with one
acquire funds for, from or to one
provide support to one.
It is also an offence to associate with a listed terrorist organisation. This is subject to certain exemptions. Anyone guilty of terrorist organisation offences can face imprisonment for up to 25 years.

Terrorist organisation offences are detailed in the Criminal Code Act 1995 which is administered by this department.

Freezing assets of organisations

As a member for the United Nations, Australia has obligations to freeze the assets of terrorists and terrorist organisations.

These obligations are implemented through Part 4 of the Charter of the United Nations Act 1945 and the Charter of the United Nations (Terrorism and Dealing with Assets) Regulations 2008.

The Department of Foreign Affairs and Trade administers these Acts.

https://www.ag.gov.au/nationalsecuri...nisations.aspx