Every year, under the law known as the Bank Secrecy Act, you must report certain foreign financial accounts, such as bank accounts, brokerage accounts and mutual funds, to the Treasury Department and keep certain records of those accounts. You report the accounts by filing a Report of Foreign Bank and Financial Accounts (FBAR) on FinCEN Form 114.
Who Must File
A United States person, including a citizen, resident, corporation, partnership, limited liability company, trust and estate, must file an FBAR to report:
a financial interest in or signature or other authority over at least one financial account located outside the United States if
the aggregate value of those foreign financial accounts exceeded $10,000 at any time during the calendar year reported.
Generally, an account at a financial institution located outside the United States is a foreign financial account. Whether the account produced taxable income has no effect on whether the account is a “foreign financial account” for FBAR purposes.
But, you don’t need to report foreign financial accounts that are:
Correspondent/Nostro accounts,
Owned by a governmental entity,
Owned by an international financial institution,
Maintained on a United States military banking facility, 
Held in an individual retirement account (IRA) you own or are beneficiary of,
Held in a retirement plan of which you’re a participant or beneficiary, or
Part of a trust of which you’re a beneficiary, if a U.S. person (trust, trustee of the trust or agent of the trust) files an FBAR reporting these accounts.
You don’t need to file an FBAR for the calendar year if: 
All your foreign financial accounts are reported on a consolidated FBAR. 
All your foreign financial accounts are jointly-owned with your spouse and:
You completed and signed FinCEN Form 114a authorizing your spouse to file on your behalf, and your spouse reports the jointly-owned accounts on a timely-filed, signed FBAR. 
Note: Income tax filing status, such as married-filing-jointly and married-filing-separately has no effect on your qualification for this exception.
The FBAR Reference Guide PDF) and FBAR instructions PDF  provide more detailed information. The FBAR webinar explains how to calculate the aggregate value of your accounts to figure if you need to file an FBAR. 
When to File
The FBAR is an annual report, due April 15 following the calendar year reported. 
You’re allowed an automatic extension to October 15 if you fail to meet the FBAR annual due date of April 15. You don’t need to request an extension to file the FBAR.
If you are affected by a natural disaster, the government may further extend your FBAR due date. It’s important that you review relevant FBAR Relief Notices for complete information.
For certain employees or officers with signature or other authority over, but no financial interest in certain foreign financial accounts, the 2018 FBAR due date is deferred to April 15, 2020. See Notice 2018-1 PDF.
How to File
You must file the FBAR electronically through the Financial Crimes Enforcement Network’s BSA E-Filing System. You don’t file the FBAR with your federal tax return. 
If you want to paper-file your FBAR, you must call FinCEN’s Regulatory Helpline to request an exemption from e-filing. See Contact Us below to reach this Helpline. If FinCEN approves your request, FinCEN will send you the paper FBAR form to complete and mail to the IRS at the address in the form’s instructions. IRS will not accept paper-filings on TD F 90-22.1 (obsolete) or a printed FinCEN Form 114 (for e-filing only). 
If you want someone to file your FBAR on your behalf, use FinCEN Report 114a PDF, Record of Authorization to Electronically File FBARs, to authorize that person to do so. You don’t submit FinCEN Report 114a when filing the FBAR; just keep it for your records and make it available to FinCEN or IRS upon request.