
General tax questions can often be answered by the department responsible for personnel matters at your place of employment.
The authority responsible for your taxation is the
local tax office 
("örtliches Finanzamt").
In many cases, it is worth consulting a tax accountant. In addition, many towns in Germany have
Income Tax Advisory Societies 
("Lohnsteuerhilfevereine") which offer inexpensive counselling.
Advisory service for EU citizens concerning residence permits, social security, taxes etc. is available free of charge through a team of legal experts at
Citizens Signpost Service.
Furthermore, you can approach EURAXESS Germany/National Coordination Point at the Alexander von Humboldt Foundation:
info@avh.de. We can provide you with general information and help you to make the right contacts.