This will depend on the bilateral tax agreement between the country employing you and the country where you work (the "host" country). Most EU countries have opted for the rule whereby, as a civil servant, you pay taxes only in the country which employs you.
Exception: You may be required to pay taxes in the "host" country if you are required by your employer to work there and either:
This is only a summary of the most common rule. There could be exceptions to this rule in some international tax conventions. Ask your tax office or a European employment adviser and consult the relevant bilateral tax agreement.
YES — You should be entitled to the same tax deductions as residents of your "home" country — if your salary as a civil servant is almost the entire income of your household.
However, if your spouse also works and earns significant income in the "host" country, this might nullify your entitlement to home-country deductions. In that case, the deductions to be applied to your total household income would be those available under the host-country law.
You would not, in any event, be entitled to two sets of deductions.
If you feel discriminated against, you should seek redress from the national authorities. Depending on the nature of the problem, you could also seek assistance through the EU citizen's assistance services.