Depending on whether or not you are tax residents of a country that includes exchanges of information you will behave in different ways. If you open an account as Italian residents or any other European country, you must always indicate every year, in the appropriate framework of your tax return, the possession of the offshore account and its stocks when they exceed 10,000 euros of against value. If you are a residents of a country with subsidized taxation like
Panama you don't have to declare anything.