Member States in the European Union (EU) are responsible for National Allocation Plans governing the initial distribution of emission allowances in the CO2 Emission Trading System, including rules governing allocations to installations that close and to new entrants. The European Commission has provided guidelines to discourage the use of allocation methodologies that provide incentives affecting firms' compliance behavior, for example by rewarding one type of compliance investment over another. We find that the treatment of closures and new entrants by Member States is inconsistent with the general guidelines provided by the EU. We propose stronger EU guidance regarding closures and new entrants, a more precise compensation criterion on which to justify free allocations, and a Ten-Year Rule as a component of future EU policy that can guide a transition from current practice to an approach that places greater weight on efficiency. (c) 2006 Elsevier Ltd. All rights reserved.