Any US tax resident with a financial interest in, or signature authority over, a foreign financial account is required to file this form, "Report of Foreign Bank and Financial Accounts" (commonly called FBAR), if the value of the assets in the account exceeds $10,000 at any time during a tax year. The form is filed electronically at the website of the Financial Crimes Enforcement Network (FinCEN) and is due by June 30 of the year following the tax year when the reporting was triggered. For details, see the related FAQ.
Alert: Starting with FBAR reporting for the 2016 tax year, the annual deadline for the filing of FinCEN Form 114 has changed from June 30 to April 15. Therefore, the first due date for reporting under the new deadline is April 15, 2017. A six-month extension of the filing deadline (i.e. until October 15) will become available when the new due date takes effect.