The taxation of cross-border corporate activities and the associated obstacles to loss offsetting are among the central and yet unresolved issues of international tax law. The case law of the European Court of Justice, primarily triggered by the Marks & Spencer ruling, has created an urgent need for action for EU member states, particularly Germany. In parallel to this development, the European Commission has identified the restrictions of purely national loss offsetting systems as one of the significant tax barriers within a single market and has announced further efforts in this area. Ansas Wittkowski analyzes cross-border loss offsetting systems in selected EU member states based on economic, European, and constitutional criteria. Building on this, he develops proposals for a unilateral approach.