在全球化與人口結構變遷的趨勢下，外籍低技術勞工已成為許多國家彌補勞動力缺口的關鍵來源。本文針對包含本國高技術勞工、低技術勞工與外籍低技術勞工的異質性勞動結構，建構一個無窮期的Ramsey 租稅模型，以探討社會制定者在追求社會福利最大化下，最適資本稅與勞動稅的設計。研究發現，勞工異質性與稅制限制導致最適資本稅率不再為零，且其大小與各類勞工之間的關係密切相關，並且當政府對外籍勞工施加稅後薪資下限等政策限制時，亦會對最適資本稅率產生實質影響，顯示資本稅在扭曲勞動市場結構下可能成為調節手段之一。

In the context of globalization and demographic shifts, low-skilled foreign labor has become a crucial source for filling labor shortages in many countries. This paper constructs an infinite-horizon Ramsey taxation model incorporating a heterogeneous labor structure consisting of domestic high-skilled workers, domestic low-skilled workers, and low-skilled foreign workers. The aim is to explore the optimal design of capital and labor taxes under a social planner’s objective of maximizing social welfare. The study finds that labor heterogeneity and tax policy constraints lead to a non-zero optimal capital tax rate, which is closely related to the composition of the labor force. Moreover, government interventions such as wage floors for foreign workers can significantly influence the optimal capital tax rate. These findings suggest that capital taxation may serve as a policy tool to adjust for distortions inthe labor market structure.

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