In addition to answering aquestion on Schedule B of their 1040s asking if they own or have control over foreign accounts and reporting all the taxable income from those accounts, U.S. taxpayers are required to file annually with the U.S. Treasury a (once obscure) form known as a Report of Foreign Bank and Financial Account or FBAR.
On the Form 1040 federal income tax return, at Schedule B, Part III, there is aquestion asking whether the taxpayer has an interest in financial accounts in a foreign country.