Pre-existing accounts of less than $50,000 don’t need to be reported. FFI may look at any U.S connection however, for example, U.S address, telephone number, U.S passport should the threshold be exceeded (aggregated). Any new account opened, unless exempted will ask if you’re a U.S person as part of the take on procedure, (some FFI's will ask this for any initial deposit, even under 50K). So this far reaching law could have implications for not only USC’s GC Holders, but others that are considered U.S persons for tax purposes. S Corp, E2, H1B visa holders come to mind. I would hazard a guess here, but if you file a 1040 and not a 1040NR, you would come under FATCA