The FBAR filing threshold is an aggregate amount–meaning, if you have multiple accounts, the total balance of all of your accounts is what would trigger a filing requirement. Assuming that you had 2 foreign accounts during the year  - account A had $3,500 and B had $7,000 as the highest balance.  As the combine balance ($3,500 + $7,000 = $10,500) exceed $10k lime there is FBAR need to file including both the accounts.