What form is used to let the payor know that a treaty exists?
Alien students, teachers, and researchers who perform dependent personal services (as employees) can use Form 8233, Exemption From Withholding on Compensation for Independent (and Certain Dependent) Personal Service of a Nonresident Alien, to claim exemption from withholding of tax on compensation for services that is exempt from U.S. tax under a U.S. tax treaty. See Form 8233 for more information.