Allison Christians (Wisconsin) has posted Taxing the Global Worker: Three Spheres of International Social Security Coordination, 26 Va. Tax Rev. ___ (2006), on SSRN.  Here is the abstract:

Social security is a fundamental part of every U.S. worker’s life in three spheres: contributions are required, benefits are hoped for, and taxes on benefits may have to be paid. If a worker splits a career between several countries, each of these three spheres is affected. International coordination has been achieved sporadically and inconsistently through a combination of treaties and executive agreements that address the three spheres in various ways. The result is a group of overlapping and potentially dueling agreements that raise myriad interpretational issues and create uncertainty for workers and administrators. This article argues that rationalization of international social security coordination requires adoption of different institutional choices at the national and international level.