Tax issue for having Austria as third country (Vienna)

Hi!,

I spent 5 years in Vienna working for an International company.
First 4 years my center of vital interest was home country, Romania.
In the last year I applied for child benefit because my son is living and learning in Austria.
As result of this I change my center of vital interest in Austria.
From Tax point of view was no difference while Austria are taxing my Austrian income. The difference will be for some international income which I do not have.
Starting with this year I moved to Pakistan on an international contract between Romania (home country) and Pakistan (host country)
Austria remain my centre of interest and become third country, that mean Austria can tax my income worldwide but not Pakistan income that will be between home and host country.
My spouse could join me to Pakistan but I would like to continue to keep rented apartment for my kid Protected content school.
In fact I will not have any income in Austria.
Do I need to pay a tax adviser in this case? Can I still have child benefit if no taxation will be perform by Austrian state? How expensive is a tax adviser for helping with yearly tax reporting?
Thank you,
Catalin