If you are a U.S. person (citizen, alien resident, or green card holder) and the aggregate maximum value of your foreign bank and financial accounts exceeds 10,000 USD during any year, you have an FBAR reporting requirement for that year. This reporting obligation extends to a wide variety of accounts (bank accounts, time deposits, investment accounts, life insurance policies, and retirement accounts) - see this article for an overview of the types of accounts requiring account or asset reporting (future article coming soon) but equally importantly, it also extends to a wider variety of circumstances than a reasonable person would expect.
The maximum value of the accounts in which you have a financial interest are added to the maximum values of the accounts in which you have a signatory interest, and your reporting obligations include both types of accounts. For example, if you have one foreign bank account with a maximum value of 500 USD and your mother has an account that she has given you power of attorney or signatory authority over that has a maximum value of 9,501 USD, then you will have an FBAR reporting requirement.
FBAR requirements are based on maximum balances and these maximum balances do include inter account transfers. For example, if you have four foreign accounts, one in Italy, one in Spain, one in Switzerland and one in France, and as you travel between these countries throughout the course of the year you transfer your roughly 3,300 USD from account to account to fund your travels, you will have an FBAR reporting requirement. You will have to report a maximum balance for each account of your roughly 3300 USD, giving you a maximum aggregate value of 13,200 USD.
You cannot split the value on jointly held accounts. For example, if you and your spouse are joint on a foreign account worth 11,000 USD, you both have an FBAR requirement(although in some cases it is possible to satisfy both FBAR requirements with one filing).
If you have reason to believe that you are over the 10,000 USD threshold, you have to include accounts even when you don’t know and cannot determine the value of those accounts. For example, if you have a bank account with 10,001 USD and three accounts you are unable to ascertain balances for, you must still include all four accounts on your FBAR, and there are circumstances in which the unknown account values could lead to the filing of an FBAR even though you may be under the 10,000 USD threshold without accounting for the balances of those accounts.
If you have never filed an FBAR and assume that this reporting requirement does not extend to you, I encourage you to ask yourself two questions - am I a U.S. person and is the aggregate value of my foreign accounts over 10,000 - If the answers to both of these questions are yes, then you need FBARs. Too many people assume that because they have never filed an FBAR that it isn’t required of them for one reason or another, and this deliberate ignorance can ultimately be incredibly costly, resulting in penalties that can be as high as 50% of the account values.
FBARs have a strict statute of limitations of six years. This six years runs from the original due date of the FBAR. For example, the 2011 FBAR was due on June 30th 2012, and this means the statute of limitations for assessments on that FBAR expired on June 30th, 2018. This also means that you only need to be concerned with correcting up to six years FBARs. The annual FBAR deadline has changed from June 30th to October 15th, but may change to April 15th in the future.