No idea. In fact, my idea is that the whole place belongs to the Grimaldis and some other few families. Common people work for their companies and have to pay their taxes for ...services,insurance, pensions and so on. So, you work for me, I pay this salary and then you have to give me back some of it because.
Wikipedia says no tax on individuals, which leads me to believe that there are taxes on businesses. Monaco also had a little problem with money laundering, especially through the casino, a few years ago. So the fees from that service might support a few endeavors if that is true.