作者
顏志達^* (國立臺中科技大學財政稅務系)
翁堃嵐 (國立政治大學財政學系)

Authors
Chih Ta Yen^* (Department of Public Finance and Taxation, National Taichung University of Science and Technology)
K. L. Glen Ueng (Department of Public Finance, National Chengehi University)

中文摘要
本文建構了一個包含消費外部性的個人自我保險模型，文中有二項主要的發現。第一，當個人偏好為妒忌 (jealousy) 且為風險趨避時，個人均衡的自我保險投入會低於社會的最適水準，此一結果明顯異於 Dupor and Liu (2003) 的論點。第二， 當個人均衡屬於低度（過度）自我保險時，假若政府資金的邊際成本 (marginal cost of public funds, MCPF) 等於 1，則政府可透過對個人的損失課稅（扣 除），或者對其自我保險投入補貼（課稅）來矯正此一扭曲。然而，當政府資金的邊際成本大於 1 時，假若個人均衡屬於低度自我保險時，則政府應對個人的損失課稅；反之，當個人均衡屬於過度自我保險時，則應對個人從事自我保險的投入課稅。

Abstract
This paper constructs a self-insurance model in the presence of consumption externality. We have two major findings. First, if an individual is jealous and risk averse, then the equilibrium level of selfinsurance will be lower than the social optimum. This result is significantly different from that of Dupor and Liu (2003). Second, when the marginal cost of public funds (MCPF) equals one, the government should tax (subsidize) losses or subsidize (tax) self-insurance if consumers are under- (over-) insured. However, when the MCPF is greater than one, the government should tax losses if consumers are under-insured and tax self-insurance if consumers are over-insured.

中文關鍵字
消費外部性；自我保險；最適租稅

Keywords
Consumption Externality; Self-Insurance; Optimal Taxation