The article aims to provide arguments on the incompatibility between the Zero Deficit Budget and the Constitutional paradigm. European Union policies directed to deal with the economic crisis are based on the belief that the current crisis is due to the excessive levels of public expenditure. Also, European integration has been based on the imposition on European countries of policies, giving up national sovereignty, especially on economic issues. It is worth mentioning that those constraints are carried out through legal standards (often, soft law) from agents whose legitimacy is still far from being democratic. Besides, those agents are quite reluctant to accept any kind of accountability. Furthermore, EU policies have contributed to deepening the process of deconstitutionalization developed in many contemporary legal systems, especially in Europe. A long-standing process that affects to the intensity and effectiveness of constitutional rights, both political and social rights. Today European Constitutional States are far from their original intentions: democracy and the protection of human rights. The EU has imposed —through undemocratic and not transparent means— Constitutional Amendments to the Eurozone Member States aimed, on the one hand, to impose Zero Deficit Budget (that rule has become a real «golden rule»); and, on the other hand, to guarantee the payment of the public debt. Countries such as Italy and Spain have amended their Constitutions. In the Spanish case, the 2011 Amendment has included the rule of priority of debt payment (including interest debt) against any social costs. Zero Deficit Clause, along with ensuring the position of debt holders before the citizens’ rights, jeopardizes the core of the Constitutional State, since it affects the protection and real effectiveness of the constitutional rights. Both from a «principialist» or a guarantee-based conception, the budget constraint is not consistent with the constitutional paradigm. In the first case, because it prevents the argumentation and balancing between conflicting rights that characterizes a Constitutional State. The Zero Deficit Clause is defined not as a principle, but as a rule. In the second case, because it introduces a new element into the «undecidable realm» (defined by Luigi Ferrajoli) with all their primary and secondary guarantees. Therefore, the article concludes with the assertion that the imposition of a Zero Deficit Clause means the end of the Constitutional paradigm.