If you have checked your country's treaty with the U.S. and
have found you qualify for a treaty exemption on your wage or
scholarship income, you must file Form 8233, Exemption From Withholding
on Compensation for Independent (and Certain Dependent) Personal
Services of a Nonresident Alien Individual, with the payor of
the exempt income. You must include with Form 8233 a statement
detailing your eligibility for the specific tax treaty exemption.
You will find sample statements for each treaty country in Publication
519, Appendix A (for students) and Appendix B (for teachers and
researchers). Form 8233 and Publication 519 can be downloaded
from the U.S. Treasury's Forms and Publications site, or you can
call 1-800-TAX-FORM (1-800-829-3676) and ask for them to be mailed
to you.