>>3
I'm just throwing it out there. Rich people from other countries would move to the country importing everything they need to their corporate headquarters and condominiums, at the same time employers would have to increase wages so workers can pay for their citizenship so in the end, as long as you work, it's a pretty equal system. I admit this is a bit mercantilist but it's not the tax haven's fault that other countries can't compete.
Another idea would be for people to pay for their services from the government. For instance clean apartment complexes with their own security systems would pay less tax than crime ridden ghettos because they are less dependant on police protection, poor people would have an incentive to move to areas where they can be controlled more easily and won't turn to drugs or crime. If you live out in the countryside and grow your own food you could be paying virtually no tax except for a token amount for national defense. Whereas if you own 51% of a major energy corporation and several large homes across the country you will have to pay a fuckton of tax for all the state services you need to regulate it aswell as keep order.