The US has income tax treaties with many different countries. These treaties either reduce or exempt income tax on a portion of the eligible foreign national's earnings. They are based on your country of foreign residence, not your country of citizenship or birth, and vary in their terms and scopes. Most involve exempt dollar limits, which is the amount of earnings that can be exempt from income tax withholding. Any wages earned over the exempt dollar limit will have income tax withheld. Different treaties may also involve an exempt time limit, which is the number of years a foreign employee can use the income tax treaty. This time limit begins at the date of arrival in the US, not the first year the tax treaty exemption is claimed.
Treaties are only applicable to Non-Resident Aliens for tax purposes. In order to claim a tax treaty exemption, you must submit IRS Form 8233 to your employer prior to starting your employment and at the beginning of each new tax year. For payments from the University of Rochester, if are eligible and choose to claim a treaty benefit, GLACIER will generate this form for you. Alternatively, please refer to IRS instructions in order to fill out your Form 8233.
For more information on tax treaties, please read IRS Publication 901.