Fiscal sustainability and its implications for monetary policy

财政可持续性是我们这个时代最重要的宏观经济问题之一。最近，由于COVID-19疫情后公共债务迅速增加，这个话题变得更加突出。在这种背景下，债务比率的爆炸性增长主要是由于政府实施了前所未有的救助计划和刺激计划。目前的研究仍处于从多个角度理解和分类COVID-19大流行的过程中。最终，衡量一个经济理论成功与否的标准是它对经济发展的概念化、描绘和解释能力。新凯恩斯主义（NK）模型框架是研究商业周期以及货币和财政政策的最重要和最广泛使用的方法之一。然而，在研究债务比率和可持续财政政策的影响时，简单的NK模型框架存在明显的缺陷。这主要是因为债务和财政政策基本上与模型动态和模型预测无关。关于开放的问题和批评的观点，我们希望在这个项目中制定解决方案。在第一个供资阶段开发的FTPL-NK参考模型表明，大规模刺激计划和高负债率的后果可以用经验发展来解释。考虑到风险溢价，就有可能对可持续财政政策的传导渠道有新的认识，估计参数，并将模型预测与经验数据进行比较。特别是，我们希望调查对货币政策设计的影响，并制定新的战略来管理甚至避免债务危机。金融危机与COVID-19疫情之间的时期，大部分发达经济体的真实的利率持续处于低位，而经济则保持高速增长。这就提出了一个问题：在这种情况下，债务是否有财政成本，这对货币政策意味着什么，以及在多大程度上维持可持续性需要通过提高税收或降低支出来最终降低高负债率。可持续性对任何国家来说都是一个无所不在的挑战，无论其发展水平如何。特别是在由于固定汇率而无法实行完全独立的货币政策的小经济体中，财政政策工具具有不可或缺的重要性。然而，这也可能受到保持可持续性的限制。在此背景下，我们希望研究对货币政策设计的影响，并制定新的经济政策战略，为应对未来的债务和货币危机留下最大的回旋余地，从福利经济学的角度来看是最佳的。

Fiscal sustainability is one of the most important macroeconomic issues of our time. This topic has recently become even more prominent due to the rapid increase in public debt in the wake of the COVID-19 pandemic. In this context, the explosion in debt ratios is primarily due to the implementation of government bailout programs and stimulus packages of unprecedented magnitude. Current research is still in the process of understanding and classifying the COVID-19 pandemic from a variety of perspectives. Ultimately, the success of an economic theory is measured by how well it can conceptualize, map, and explain economic development. The New Keynesian (NK) modelling framework is one of the most important and widely used approaches to study business cycles as well as monetary and fiscal policy. However, the simple NK model framework has significant weaknesses when studying debt ratios and the impact of sustainable fiscal policy. This is mainly because debt and fiscal policy are basically irrelevant for model dynamics and model forecasts. With reference to the open questions and points of criticism, we want to develop solutions in this project. The FTPL-NK reference model developed during the first funding phase shows that the consequences of large-scale stimulus packages and high debt ratios can be explained consistently with empirical developments. The consideration of risk premiums opens up the possibility of gaining new insights into transmission channels of sustainable fiscal policy, estimating parameters and comparing model forecasts with empirical data. In particular, we want to investigate the influence on the design of monetary policy and develop new strategies to manage or even avoid debt crises. The period between the financial crisis and the COVID-19 pandemic was characterized by a sustained period of low real interest rates and high economic growth in most developed economies. This raises the question of whether debt has fiscal costs in this situation, what this means for monetary policy, and to what extent maintaining sustainability requires that high debt ratios be ultimately reduced through higher taxes or lower spending. Sustainability is an omnipresent challenge for any country, regardless of its level of development. Especially in small economies, which cannot pursue a completely independent monetary policy due to fixed exchange rates, fiscal policy instruments take on an integral importance. However, this can also be limited by the preservation of sustainability. Against this background, we want to examine the influence on the design of monetary policy and develop new economic policy strategies in a way that leaves the greatest possible room for maneuver for coping with future debt and currency crises and are optimal from a welfare economics perspective.