Answer:
The Foreign Account Tax Compliance Act (FATCA) began in 2015 as an attempt to create tax reporting exchanges with foreign countries. It created Chapter 4 in the Internal Revenue Code. The actual data exchanges will need FTINs so that the foreign government knows who the interest belongs to for tax purposes. The same will be said for US persons with foreign accounts.
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Learn more about Deborah Crawford’s webinar Nonresident Aliens Deposit Customers: FTIN, US TIN and Interest Reporting