FATCA is incorporated in Dutch law and as a result, DEGIRO is obliged to verify whether its clients are considered U.S. Person. DEGIRO is obliged to share this information with the Dutch tax authorities. Subsequently, the Dutch tax authorities shares this information with the US Internal Revenue Service.
FATCA is somewhat similar to CRS, but then specifically to fight against tax evasion in the United States. FATCA ensures that ‘U.S. Persons’ file a (complete) tax return with the US Internal Revenue Service that also contains their assets maintained at financial institutions outside the United States.