COVID 19 travel restrictions change depending on the current COVID 19 situation in Australia. Please ensure you keep up to date on the current restrictions on the Tasmanian government coronavirus page. 

https://coronavirus.tas.gov.au/travellers-and-visitors/coming-to-tasmania

You must register prior to arriving on King Island.

Depending on where you have been you may have to use either the Tas-e-travel system – https://arrivals.dpipwe.tas.gov.au/Pages/default.aspx

or the G2G pass.  https://g2gpass.com.au/tasmania