The minimisation of the tax burden of expatriates is a fundamental part of a companys planning of international assignments. In several countries, expatriates are subject to special tax privileges which intent on attracting companies and highly qualified from abroad. International assignments and the tax burden on international assignments are an often discussed topic. However, up to now there is neither a scientific and comprehensive analysis on tax and social security regulations for expatriates nor a method which quantifies the tax burden on international assignments. The scope of this study therefore is to analyse qualitatively and quantitatively the locational conditions regarding the taxation of expatriates in selected countries in Europe and the United States. In a methodological respect we extent the ZEW simulation model which measures the tax burden on highly skilled manpower to cross-border assignments.