Definition:
Foreign Account Tax Compliance Act (FATCA) Withholding refers to amounts required to be withheld on payments subject to withholding under chapter 4 of the Internal Revenue Code. A withholding agent must withhold on a payment of U.S. source fixed, determinable annual, or periodical (FDAP) income that is a withholdable payment and to which an exception does not apply.
Chapter 4 defines withholdable payments and exceptions. See Page 4