For added facts on withholding on winnings, refer to Publication 515, Withholding of Tax on Nonresident Aliens and Foreign Entities. https://www.google.lu/url?sa=t&url=http%3A%2F%2Fjustbevictorious.com%2F%ec%b9%b4%ec%a7%80%eb%85%b8%ec%82%ac%ec%9d%b4%ed%8a%b8%ec%9d%98-%eb%a7%a4%ed%98%b9%ec%a0%81%ec%9d%b8-%ec%84%b8%ea%b3%84-2%2F