People arriving in Australia at the moment must self isolate for 14 days after arrival, no matter where they come from.
This is in effect from Sunday 16th March 2020.
It is to try to help in stopping the spread of the Covid-19 coronavirus.
To enforce the self isolation rule, each Australian state can impose penalties for anyone who breaks the isolation (quarantine) period.
Penalties for not Self Isolating in Australia are up to:
WA: $50,000 plus 12 months jail
NSW: $11,000 plus 6 months jail