累進所得稅對比消費稅：應對臺灣人口老化與不平等加劇

Progressive Income vs. Consumption Taxation: Tackling Taiwan’s Aging Population and Rising Inequality

本文旨在比較累進所得稅與消費稅，在臺灣面臨人口老化與所得收入不均加劇的背景下，對社會福利與財政永續性的差異性影響。本文建立一套動態一般均衡模型，並根據臺灣的人口趨勢、勞動生產力、稅制結構與年金制度加以校準，以推導可維持年金永續性的最優稅制改革。研究結果顯示，提高所得稅的累進程度，對高所得者課徵較高稅率，可帶來顯著的社會福利增益與年金稅率的明顯下降，主要來自於所得重分配效果，而非行為反應。然而，此政策亦伴隨不可忽視的總體經濟代價，包括產出與資本投入的減少。相較之下，最優消費稅制改革帶來的福利改善較小，因其無法產生足夠的分配效應及稅收收入，以有效紓緩人口老化所造成的財政壓力。綜上所述，雖然累進所得稅在促進平等與維持年金永續性方面具優勢，政策制定者仍需審慎權衡其潛在的效率損失與經濟成本。

This paper compares the differential impacts of progressive income and consumption taxation on welfare and fiscal outcomes in the context of Taiwan’s aging population and rising income inequality. Using a dynamic general equilibrium model calibrated to Taiwan’s demographic trends, labor productivity, tax structure, and pension system, it derives optimal tax reforms that maintain pension sustainability. Results show that greater income tax progressivity featuring higher rates on top earners yields sizable welfare gains and significant reductions in the pension tax rate, driven primarily by redistribution rather than behavioral responses. However, these benefits come at non-negligible costs, including reductions in output and capital accumulation. By comparison, optimal consumption taxation provides smaller welfare improvements as it fails to generate sufficient redistribution or revenue to relieve the rising fiscal pressure. These findings suggest that while progressive income taxation effectively addresses inequality and pension sustainability, policymakers must carefully weigh these benefits against potential efficiency losses.