隨收隨付制年金與勞動內生化：疊代經濟的分析

Abstract

本文擬修改Heijdra (2009)的模型假設，並參考Ihori (1996)與金志婷 (2011)的處理方式，建立一個以線性所得稅融通之隨收隨付年金的疊代模型。在考慮勞動外生化以及勞動內生化兩種情況下，分別探討所得稅率變動以及人口成長率變動將會如何影響經濟體系的總體均衡，並得到以下結果：\n一、勞動外生化模型中，政府提高隨收隨付年金的所得稅率將會影響民眾的儲蓄行為而不利於每人資本的累積。\n二、不同於Heijdra (2009)勞動供給量為常數的結果，本文的勞動內生模型將涉及勞動的差分方程式。同時，在總體均衡下此經濟體系會存在多重均衡，而發生均衡的不確定性，當政府提高所得稅率，將會造成長期均衡的勞動量和資本勞動比都同時降低。\n三、不論勞動外生或是勞動內生模型，人口成長率降低皆有助於每人資本及資本勞動比的增加。

Based on the Ihori (1996) analysis, this thesis makes a revision from Heijdra (2009), and develops a simple two-period overlapping-generations model with a Pay-as-you-go pension and linear income taxation. This thesis then analyzes the dynamic properties of the model and how the change in the income tax rate and the population growth rate affect the household’s optimizing behavior and the economy’s capital accumulation. The analysis includes both the exogenous labor supply case and the endogenous labor supply case. \n\nSeveral main findings emerge from the analysis. First, in the presence of exogenous labor supply, a rise in the income tax rate leads to a negative impact on private savings and decreases physical capital per capita. Second, in the presence of endogenous labor supply, running in contrast to Heijdra (2009), labor supply would not be a constant but relates to its amount in the next period. As a result, coupled with the difference equation in capital-labor ratio, the simultaneous difference equations in both labor supply and capital-labor ratio are present in the overlapping-generations model. By imposing some plausible conditions, it is found that the overlapping generations economy exhibits local indeterminacy and a rise in the income tax rate would reduce both the capital-labor ratio and labor supply in the long run. Third, a reduction in the population growth rate would stimulate both physical capital per capita and the capital-labor ratio, regardless of whether labor supply is exogenous or endogenous.