Oklahoma State University is required by the U.S. Internal Revenue Service (IRS) to withhold federal income tax from ALL payments made to (or on behalf of) a nonresident alien. Regulations also require that Oklahoma State University report all such payments to the IRS. Therefore, Oklahoma State University must review all data related to the immigration status and purpose of their stay of all payment recipients at Oklahoma State University who are not U.S. citizens or lawful permanent residents. Determining tax residency and tax treaty eligibility is a complicated and difficult task which is why Oklahoma State University uses tax compliance software called GLACIER.