If you specified the particular university in question that may help. However, for federal tax purposes, all organizations are classified as either a partnership, trust, or corporation. Purely governmental organizations, like the U.S. Congress are not taxed and thus have no need for tax classification. Colleges and Universities, though, are not purely governmental organizations, i.e. they do not carry out purely governmental activities like making and enforcing the law. They are instead organizations that compete with private universities that do the same thing. For that reason, they are subject to U.S. tax unless they qualify for tax exemption, usually under Internal Revenue Code (IRC) § 501(c)(3). And in general to get that exemption, they must be a corporation for federal tax purposes. For example, the University of Colorado (CU) is a state university officially organized as the Regents of the University of Colorado, a corporation exempt under § 501(c)(3). So an employee of CU working in China would not be exempt from Medicare taxes. This will be the case for pretty much every state university. But like I said, the details of the particular university in question matters.