The U.S. IRS has published a practice unit on Deferred Compensation Received by Nonresident Alien Individuals. The general overview of the practice unit includes the following:
Generally, nonresident alien (NRA) individuals are taxed on effectively connected income (ECI) and U.S. source fixed or determinable, annual, or periodic (FDAP) income. ECI is earned from the operation of a U.S. trade or business, including from the performance of personal services in the United States, and is taxed …