If you’re an American citizen and own a Swiss bank account, there’s a good chance you’ll be receiving a letter from the Swiss bank politely asking you to take your business elsewhere. A pending U.S. regulation, known as the Foreign Account Tax Compliance Act, or Fatca, requires foreign banks to identify Americans among their clients and to provide their financial information to the Internal Revenue Service. A devastating penalty equivalent to 30% of a bank’s U.S. income could be assessed if even one person is overlooked. Swiss banks are particularly on edge, as the U.S. has alleged that 11 Swiss banks have helped Americans avoid paying taxes. As a result they have begun ushering American clients out or limiting the range of products offered to them. The administrative cost of complying with the law, given the relatively small number and size of U.S. accounts, just isn’t worth it. While the impact can already be felt in Switzerland, banks world-wide are also concerned about the complexity of the new rules, and the difficulties and costs involved with Fatca, whose full enactment is viewed as inevitable.