With so many data breaches happening in recent years, our private information is now in the hands of criminals.
It is my understanding that ATO enables the linking of multiple mygov accounts so long as the account provides 100 point identification.
In theory and in practice, a criminal that has stolen a victim's identity can create a mygov account, and link to ATO, amend/change tax information and even drain super. I've seen reports of this happening to people, without even receiving a notification or alert that a new account has been linked, amendments have been made to their tax return, or their super has been rolled over to an SMSF to be drained.
This is very worrisome.
ATO should have provisions to enable restriction of linking to multiple accounts, notifications and alerts, etc. so that people can be proactive in case of a breach.