Proportionate to the share of the national wealth that they control or the damage that they do, they are still not paying their share. There is simply no way to earn an honest living without putting some burden on the commons or exploiting the labor of others. If you are not paying a decent, living wage, and not cleaning up your slop behind you, you are stealing labor and fouliong your own nest, and you owe something back to society.
A fair rate of individual income tax would be about a percentage point of tax for every ten percentage points by which the income being taxed excedes the modal income for the nation, assuming that there is no current emergency which requires immediate government action and emergency funding.
This leaves small business people and the average worker free of any heavy tax burden until they actually start to acquire some sort of material wealth. It leaves more money in the communities in which the small entrepreneur and the working person are generating wealth and where ecconomic activity is more easily monitored and regulated by local governments. The larger and more wide-spread corporations, of course, are only subject to federal regulation and oversight, and that adds a lot to the cost of regulatory agencies. There is no reason that the local yokels should have to pick up that cost. They could not even afford to cover it to any extent.
Corporations should be taxed at a flat rate on all profits not paid out to tax-paying entities within the jurisdiction of the USA.
Anchoring the tax rates to the modal rather than mean income is crucial here to achieve fairness, because it kicks in at a relatively low income level at a bearable level, as long as everyone is doing well, and then becomes more of a burden on the high earners when things start to go badly. The more the middle class makes, the less the Two-percenters pay proportionately. The less the middle class makes, the steeper the increase in the taxes on the Two-percenters until it levels out again.