You fill out a tax declaration every year. If you don't disclose some values and this is discovered later on, you will be punishable with a fine (between 30% an

You fill out a tax declaration every year. If you don't disclose some values and this is discovered later on, you will be punishable with a fine (between 30% and 300% of the tax on the non-disclosed values). The fine can be avoided in some cases by self-indictment, but of course you'll still have to pay the avoided taxes plus interest. If you even fake documents to avoid taxes, then you can end up in jail. This system of "voluntary" tax declarations is like a contract between the government and the citizens: Government doesn't stick their nose into bank accounts of citizens, while citizens pay taxes on their assets. I'm not sure if it's a good system, but it has mostly worked out so far.