A quantitative analysis of the tax and social security systems in an aging Japan

随着人口迅速老龄化，日本面临着严重的公共财政问题，尤其是在税收和社会保障问题上。迫切需要进行结构改革，以适应即将到来的人口变化。我们通过一个生命周期一般均衡模拟模型来研究日本的税收和社会保障制度。我们的目标是为日本老龄化社会的财政改革制定指导方针，并使用这种先进的建模技术来计算替代税收政策对资本积累和经济福利的影响。得出了以下三个主要结论。模拟结果表明，累进式支出税比累进式劳动所得税更能刺激资本积累。因此，这种新的税收制度可能是克服当前税收制度下日本社会老龄化所带来的巨大福利损失的关键。我们还研究了日本现行税收和社会保障制度的理想税收组合。结果表明，在收入中性的条件下，提高消费税税率和降低利息所得税率可能是一种理想的税收组合。在老龄化的日本，我们探索了一个理想的公共养老金制度。模拟结果表明，如果我们考虑与目前日本计划规模相同的公共养老金计划，当公共养老金制度仅由基本养老金组成并由消费税提供资金时，社会福利水平达到最高。我们调查了老龄化的日本的最优国民负担率。模拟结果表明，国民负担的最佳比率将随着日本的老龄化而上升，在人口快速老龄化期间可能超过50%。

With a population that is rapidly aging, Japan faces serious public finance problems, particularly when it comes to tax and social security issues. The structural reforms are urgently needed to accommodate the impending demographic change. We look at the Japanese tax and social security systems through a life-cycle general equilibrium simulation model. We aim to establish guidelines for fiscal reform in Japan's graying society and use such advanced modeling techniques to permit the calculation of the effects of alternative tax policies on capital accumulation and economic welfare.The following three main conclusions have been drawn.1. The simulation results show that a progressive expenditure tax stimulates much more capital accumulation than a progressive labor income tax. Thus, this new tax regime may hold the key to overcoming the large welfare loss Japan faces as its society ages under the current tax system. We also examined a desirable tax combination along the lines of the current Japanese tax and social security systems. The results suggest that an increase in the rate of tax on consumption and a decrease in the rate of tax on interest income may be a desirable tax combination under conditions of revenue neutrality.2. We explored a desirable public pension system in an aging Japan. The simulation results show that, if we consider a public pension program with the same scale as the current Japanese program, the highest level of social welfare is attained when a public pension system consists of only a basic pension and is financed by a consumption tax.3. We investigated an optimal rate of the national burden in an aging Japan. The simulation results suggest that an optimal rate for the national burden would rise as Japan ages, and may exceed 50% during a period of rapid aging of its population.