It is not a moral obligation.
It is only a necessary evil....that should not be overly burdensome.
I actually pay my fair share of taxes, and happily. I do not seek out every possible loophole and try to game the system. But then again I realise my taxes go to (what Americans would call) social security that pays money to the poor, elderly and those unable to work due to health, my taxes go to pay medical bills for those poorer than me. My taxes also go to public schools, roads, fire fighters and policemen.
I am more than happy to pay more than people who are poorer than me and do not look to game the system because I can afford to pay more without unduly burdening my finances.