FATCA is a US-made tax law that went into effect in 2014.
FATCA is designed to prevent US taxpayers from using offshore financial accounts to avoid complying with US tax obligations. FUTU HK is legally responsible for identifying its clients and reporting their information to the IRS.
Financial institutions, including FUTU HK.
According to the act, you are required to declare and confirm your tax identity and your financial information to us as required by FATCA.
All clients. Clients are required to complete either a W-8 form to confirm their non-US tax identity or a W-9 form to confirm their US tax identity. Only US account holders' information will be reported.
Under the current arrangement, FUTU HK is required to report its clients' information for the previous year to the IRS by March of each year.
All customers fill out the appropriate form at the time of opening an account to confirm their US tax identity and then reconfirm their US tax identity every 3 years. If there is any change during these 3 years, the customer should update the US tax status with FUTU HK as soon as possible. In addition, according to the relevant filing instructions issued by the IRS, a non-US person is subject to withholding tax in respect of certain receipts originating in the United States, and a non-US person may claim tax relief for the certain non-US person only through W-8.
See the IRS website for details, https://www.irs.gov/businesses/corporations/information-for-foreign-financial-institutions (English version only)