This paper analyses the duties and rights that the Treaty of Accession allocates to the 10 new member states of the European Union on the basis of the common European law. Since the EU of the current 15 member states did not sufficiently adjust the European institutions, the structure of competencies and the common policies to the requirements of an enlarged Union, the enlargement will not be an economic success, it considers. The reform of the Common Agricultural Policy (CAP) and the structural policies will become even more difficult within the enlarged EU of 25 or more member states; the new member states will be net beneficiaries of the CAP and the structural funds, and as such will not favour reform. The paper considers that consumers will probably not win and that taxpayers in old member states will lose. The reserves for the payment liabilities that arise from the Treaty of Accession will amount to a total of up to u0080 543 billion for the EU of the current 15 member states, of which u0080 132 billion for Germany alone over the 30 years after enlargement (assuming an annual interest rate of 5%). The expenses of the enlarged Union will rise progressively over the next 25 years until EU subsidies per inhabitant in the new member states are as high as in the current member states.