The filing requirement for foreign bank accounts applies even if the funds in the bank account were earned outside of the US and/or earned in a prior tax period.

Your tax status will determine if you have a reporting requirement. The requirement applies to U.S. citizens and resident aliens, including those with dual citizenship. If you are considered a non-resident alien, you do not have FBAR filing requirements. Individuals residing in the U.S. who do not meet one of the "United States Resident" residency tests are not considered U.S. residents for FBAR purposes.

 See https://www.irs.gov/businesses/small-businesses-self-employed/report-of-foreign-bank-and-financial-a... for more information.