The information below can be found in Publication 519 (2008), U.S. Tax Guide for Aliens.
- How a nonresident alien’s income tax is figured depends on whether the income is effectively connected with a trade or business in the United States. Income that is not effectively connected with a trade or business in the United States is taxed at the 30% rate in general.
- Personal Service Income
- You usually are engaged in a U.S. trade or business when you perform personal services in the United States. Personal service income you receive in a tax year in which you are engaged in a U.S. trade or business is effectively connected with a U.S. trade or business. Income received in a year other than the year you performed the services is also effectively connected if it would have been effectively connected if received in the year you performed the services. Personal service income includes wages, salaries, commissions, fees, per diem allowances, and employee allowances and bonuses. The income may be paid to you in the form of cash, services, or property.
- Pensions. If you were a nonresident alien engaged in a U.S. trade or business after 1986 because you performed personal services in the United States, and you later receive a pension or retirement pay attributable to these services, such payments are effectively connected income in each year you receive them. This is true whether or not you are engaged in a U.S. trade or business in the year you receive the retirement pay.