Migration zone

The migration zone is the geographical boundary of Australia's immigration control regime. The Migration Act's visa and detention requirements apply to non-citizens once they are within the migration zone. A person outside the migration zone — for example, on the high seas, in international airspace, or in a foreign country — is not subject to the Act's internal migration regime.

The concept determines when a non-citizen's status as lawful or unlawful becomes legally relevant. A person boarding a plane in London is not yet in the migration zone; upon arrival in Australia, they enter it and the Act's requirements apply immediately.

The migration zone includes:

• All Australian States
• All Australian Territories (Australian Capital Territory, Northern Territory, and external territories)
• Australian resource installations (offshore oil and gas platforms attached to the seabed)
• Australian sea installations (other offshore installations in adjacent areas)

Importantly, excised offshore places such as Christmas Island, Cocos (Keeling) Islands, and Ashmore and Cartier Islands are part of the migration zone but are designated as excised offshore places for the purposes of determining whether an unauthorised maritime arrival has "entered Australia" for visa application purposes.

The migration zone is the trigger for the Act's mandatory detention obligation under s 189. An officer who knows or reasonably suspects that a person in the migration zone is an unlawful non-citizen must detain that person. The zone is also the geographical boundary for the definition of "enter Australia" — a person enters Australia when they enter the migration zone.

The concept of "outside the migration zone" is important for applications for visas from offshore (outside Australia). Many visa subclasses may only be applied for from outside Australia; others may only be applied for from within (onshore). Some may be applied for from either location. The migration zone is the reference point for these distinctions.