10% of what? Revenue? Profit? Assets?
Companies already engage in all sorts of shenanigans to show lower profits when it suits them. [1]
Taxing revenue goes against decades, maybe centuries, of established tax law and tradition, which roughly operates on the principle "The state makes money when you make money."
If you start taxing assets, you're going to need very invasive government bureaucracy that knows everything you own, down to the last paperclip.
Anyone who claims they can make taxes simpler is either lying or doesn't understand the subject.