What is the difference between linking accounts and registering for online services?
Where you have an existing agency online account (e.g. you have a username and password that allows you to access Centrelink online services) you may “link” that agency online account to your australia.gov.au account.
If you do not have an agency online account you may register for agency online services, (i.e. Medicare and Centrelink) through australia.gov.au. You can then use your australia.gov.au user ID and password to access the agency online services.