To clear up a misunderstanding that some people may have, the tax rate only affects private corporations and the profit transfer rate only affects state controlled corporations.
You really need a 0% tax rate to attract investing CEO's if you're interested in setting up a CEO-based economy. Given that the amount of income you make from enterprises is WAY larger than the amount of income you make from taxes, it really isn't an issue. I have one very small country on FB that has it's tax rate set at 75%. It still makes 19B/month from enterprise income, and only makes 2.5B/month in income taxes.
Profit transfer is the percentage of profit that a state corporation will automatically transfer back to the state every month. I've never found a reason not to set it to 0%. Whenever a corporation has a surplus of monies (I believe it's somewhere over the 40-50B range), it automatically transfers cash back to the state, so if your corp is making a ton of money, it'll transfer back to the state anyway. If it's not making significant monies (say, due to a market downturn), I'd rather the corporation keep it's money than transfer it back to the state. It helps to minimize the number of times you might need to profit transfer money to corporation during the occasional downturn.