Report of Foreign Bank and Financial Account (FBAR).

Every US citizen who has a financial interest in or signature authority over a financial account in a foreign country  must file an  annual report if the aggregate balance in the accounts exceeds $10,000 at any time during the calendar year.

The form is form number TD F 90-22.1

The FBAR is due by June 30th of the year following the year that the account holder meets the $10,000 threshold.  The granting, by IRS, of an extension to file Federal income tax returns does not extend the due date for filing an FBAR.   There is no extension available for filing the FBAR.