My dad has no Austrlian-sourced income. He was not Australian Residency while he received his Australian tax file number. This March, his Australian permenant residence visa has approved and he is now living in Australia. And therefore, his residence status changed during FY21. When he complete his tax return this year, does he tick the box of residence or not? His whole year income from overseas will be below the threshold.
Your tax residency is different to your residency with Home Affairs. Your dad will need to check his tax residency according to our tests for tax purposes.
If this residency changed part way through the year, he will have the tax-free threshold apportioned based on when his residency changed. He'd need to say "no" to being a resident for the full year, and input the dates he was a resident for.