Taxation is something for the experts.
24.75% (used to be 24%) in Spain is the so called Beckham tax and is for ex pats who are resident in Spain. This has to be applied to through the government, however, I believe this is not available and may even of been withdrawn, despite one having a 5 year certificate of entitlement!
The normal tax in Spain depends a lot upon mortgages, kids, schools etc.
All governments are broke and pilots are easy targets, dont expect a free ride!