@JediMaster ,
for the 2021, since you left at the end of May, you probably were a Resident for Tax Purposes ( substantial Presence Test of 183 days counting all days present in 2021, 1/3rd days present in 2020 and 1/6 th days present in 2019 and for any purpose ).
Assuming that is true, you would be taxed on world income for the whole year of 2021 ( including earnings in Australia). The way out of this is to prove that (a) you left the USA on xx/xx/2021; (b) your work visa was terminated on leaving the USA and (c) since then you have had closer connection to another country, no income , no connection to USA.
If you are able to do that ( you cancelled visa/ work permit; flight ticket --one way etc., notifying INS that you have terminated your stay -- all these help) and show that all your taxes due were withheld from your earnings (US) in 2021 by your employer; then
You file a 1040 ( TurboTax works ) for year2021---TurboTax may be able to seel you a copy of 2021 tax software fro windows or MAC, just as normal covering 01/01/2021 through your day of departure, print it , date , sign and write on top DUAL STATUS FILER; then download from 1040-NR from the IRS, ( it is a fillable .pdf file) and fill this out -- essentially empty except for pertinent details . Print sign, date , write on top DUAL STATUS FILER and send the whole shebang to the IRS -- you will find address at IRS web page.
Kep copy and the documents that prove that you left the USA and severed all connection to USA. -- do not send these unless asked for .
Does this help or do you need more ?
pk
