There are two apps to set up on your smartphone for access to Australian Government departments and records:

1. MyGov: For your Tax, Covid-19 vaccination, medicare and other general personal information the app to use is MyGov. Looks like this is going to be how we all prove we are vaccinated for interstate and international travel.
2. MyGovID: However, for logging into government departments like the Tax Agent Portal or Business Tax Portal you need MyGovID. 

We just discovered today that you can actually link the two, find out more here - Using MyGovID with MyGov

This is super useful, so giving it a go now, let us know how you go!