At "Billionaire" (or even hundreds of millions of dollars) levels of wealth the government should implement a different tax scale based on net worth. Simpler and harder to manipulate. An annual minimum tax bill of 1% of your net worth that cannot be reduced, offset, deferred or otherwise mitigated per billion annually to do buisness in the country, per country.

Just stop them rorting loopholes. I think people would probably hate billionaires a whole lot less if they just paid a FAIR amount of tax.

Edit: actually the math works pretty much all the way down. Everyone should have a minimum income tax bill every year of 1% of their net worth with the only exemption being your primary residence.