Who must file a tax return?
If you are not a US citizen, you MUST file tax forms, even if you have no income.
This includes all students and research scholars at Notre Dame, especially those on F-1 and J-1 visas.
The rules and the processes are different if you have US income than if you do not. If you have income whose source is outside the US, you will follow the same rules as someone who has no US-source income.