If I earned less than the Foreign Earned Income Exclusion, do I need to file a U.S. tax return?

Yes, you must file a U.S. tax return in order to claim the Foreign Earned Income Exclusion, even if there is no resulting tax liability. In general, the exclusion needs to be claimed on a timely filed return. You may still be able to file late returns and claim the exclusion if you have not been notified by the IRS.