A card may be registered in the Cayman Islands, for example, but used regularly in Sweden for daily expenses, like groceries and clothes. In that case, the owner of the bank card probably lives in Sweden, and could be avoiding paying capital taxes in this country.
But the Tax Agency hopes that merely the threat of investigation will cause tax dodgers to come forward themselves in order to skirt expensive surcharges.
Tax paradises have come under a lot of international pressure the last several years, with Switzerland a major target. All the Nordic countries, including Scandinavia, signed an agreement two years ago with a number of such tax haven countries in order to gain more insight into hidden financial transactions there.