Books whose characters hide money in secret foreign accounts have another reason to be called fiction. The only way to do that anymore is by risking the chance of a huge penalty for a mere failure to tell good old Uncle Sammy where the money is hidden, and what the account number is.
In 1970, the U.S. government passed the Bank Secrecy Act which (among many other things) required U.S. citizens and residents to file a report that gives the location and account number of all foreign financial accounts held by or for U.S. persons. The Act introduced severe penalties for a willful failure to disclose the existence of any foreign accounts but proving that a failure to report such accounts is willful is difficult and only a few people were assessed penalties.

