To file an FBAR, check the appropriate block on your federal form 1040 at Schedule B and then file form TD F 90-22.1, Report of Foreign Bank and Financial Accounts.
To file an FBAR, check the appropriate block on your federal form 1040 at Schedule B and then file form TD F 90-22.1, Report of Foreign Bank and Financial Accounts (downloads as a pdf).
About two million people receiving only the family element of the credit will need to check their details are correct and then "file the paperwork in a safe place", as long as no changes are needed.
However, if the problem is not related to a tax preparer or software program (meaning you prepared your own return and did not check the boxes), you may need to file an amended return.