現存文獻雖已指出固定成本於不完全競爭長期分析中的重要性 (Kim, 2004),但卻未深入探討所獲得的結論，是否會因固定成本設 計方式的不同而有所不同。本文建立一個不完全競爭模型，分析並 比較既有文獻的兩種固定成本設計一生產性與非生產性固定成本 —對於最適稅率之影響。研究結果發現，政府的最適稅率會受到固 定成本的設計方式影響，顯示不同固定成本的設定在最適稅率中扮 演著關鍵角色。

The roles of fixed costs in models of imperfect competition have been extensively studied. Yet，the possibility that different types of fixed costs may lead to different implications is not systematically explored in the literature. This paper sets up a model of imperfect competition to examine whether different types of fixed costs ——production-related or non-production-related fixed costs ——influence the optimal tax rates. It is found that different types of fixed costs indeed play a crucial role leading to different implications concerning the optimal tax rates.