Something I do not catch...
This taxes rule based on HQ location is a non sense and actually forbidden in the real EU.
Start with a base at Dublin where taxes are 10% instead of 30/33% in most of EU countries, keep there 15 ATR aircrafts to maintain the base, and open bases thru Europe with no aircraft number limitations... it creates a distorsion of competition, leaving a benefit way more important for the Irish based than the other countries based competitor.
I remind major airlines such as Easyjet or Ryanair have been forced to base in countries where planes are stationed.
If Ryanair wants to pay Irish taxes and Irish salaries for a flight between, lets say, Dublin and Girona, the aircraft has to be Dublin based.
I think this rule should be changed otherwise in the games Dublin, Shannon and other Irish airports will host 80% of European airlines...