Listen, while I sympathize with your anger about corporations not paying their "fair" share, what you are proposing is, well, disasterous.
Proposing yet another level of government, one even further removed from the locus of where real power should be exercised, meaning, PEOPLE, that is where governments get their power, is dangerous at best, and at worst, insane.
The reason corporations don't get taxed? It's because they have bought and paid for the political establishments at the national level. If you set up a global taxing authority, do you know who they will tax? You can bet it won't be the corporate elites. They will end up owning the suprar-national entities, just as they own the national and state ruling elites. The only politicians they don't own are your local politicians. Mostly.
Which police do people trust more? The local sheriff, or the state boys? Same goes in politics. If you set up a global taxing authority, YOU will end up with more taxes. The corporations? They might end up with a percentage or five more, maybe. Don't count on it. THEY WILL OWN the supra-national global government. And all of those extra costs will just be passed right on down to the consumer any way.
Nope, we need to divest control of government, not increase control. We need to decrease regulation and protections of monopolies and cartels, make them compete for consumers. Right now, in the west, we live in a CORPORATE POLICE STATE.
If you want corporations taxed more? We need to do it more on the local level. The problem that this causes though, is that then corporations will flee to areas that have the least amount of taxes and environmental regulations. Well, that is the choice of each individual locality. How much do you want a corporation to rape your local environment, abuse your work force and get away with not paying it's way in the community?
That is the price of freedom.
But what gives the rest of the planet the right to tax me and my family? Really? Because taxation is THEFT. Let us not forget that, okay? Government has the legitimized monopoly on the use of force. So let us keep that monopoly on the use of force, as close to home to those we know, just our local sheriff if we can. Otherwise, we will be lorded over by those who would start wars, all for the sake of a dollar. Don't think they won't. History shows, they do, time and again.