本論文研究2008年至2017年美國三大交易所上市公司之CEO生理特徵(年紀)及人格特質(過度自信)，對於企業避稅策略之影響與其關係。本論文利用持有價內選擇權來判斷CEO是否呈現過度自信；及使用四種租稅規避指標來衡量企業避稅程度，分別為有效稅率、現金有效稅率、財稅差異與永久性財稅差異。本篇研究目的為觀察CEO年紀是否影響其過度自信程度，並進一步連結年紀效果及過度自信來探討CEO對於企業避稅策略選擇的關聯性。研究結果顯示，CEO呈現過度自信的傾向隨著年紀增加，支持保守主義(conservatism effect)。年輕CEO在沒有足夠的管理經驗及資歷下，或因為擔心影響未來職涯發展，在作決策時會持有較保守的態度，使得CEO年紀與過度自信呈現正相關。另外，在公司策略上，CEO年紀對於避稅選擇未呈現顯著影響力，過度自信則呈現顯著正相關，即當CEO有過度自信傾向時，會高估避稅利益或低估避稅成本而進行較多的避稅策略。這結果顯示，CEO的生理特徵會影響其人格特質，但在公司策略選擇上仍是以人格特質為其主要影響因素。

This study explores the impact of CEO’s physiological and personality traits (age and overconfidence) on corporate tax avoidance strategies, collecting data from the listed companies on the three major exchanges in the United States from 2008 to 2017. We use the position of unexercised options which are in the money to examine whether the CEO is overconfident or not. Moreover, we use four indicators to measure the degree of corporate tax avoidance, which are effective tax rate (ETR), cash effective tax rate (CETR), book-tax difference (BTD) and permanent book-tax difference (PER_BTD). Our research purpose is to observe whether the CEO's age affects their degree of overconfidence, and we further link the age effect and overconfidence to analyze the relation between CEO and corporate tax avoidance strategy choices. The conclusions are the CEO’s overconfident tendency increasing with age and support the conservatism effect. Due to lacking of management experience or worrying about the future development of careers, younger CEOs tend to be more conservative, making the CEO's age positively correlated with overconfidence. In terms of company strategies, there is no significant correlation between CEO’s age and tax avoidance, and overconfidence is significantly positively correlated with tax avoidance. If the CEO is overconfident, he or she will overestimate tax avoidance benefits or underestimate tax avoidance costs and conduct more tax avoidance activities. These results reveal that the CEO’s physiological characteristics will affect their personality traits, but only the personality traits are the influencing factors in the corporate strategy choices.

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