資本利得課稅的問題，在各國間一直被猛烈的爭論著，或以失之過寬，或以失之過嚴 ，立場各異，見解自殊。然而，經濟在進步，觀念在改變，稅制亦隨之革新，本文乃 以客觀立場，對有關問題，加以多面的探討。 全文分為六章十八節及附錄一則，合成一冊，近六萬言。 第一章緒論，說明本文研究動機與全文結構。第二章，由資本利得的本質；應否課稅 ；應輕稅或重稅，來探討資本利得課稅在理論上的一些爭議。第三章，分別就資產流 通、投資結構、消費與儲蓄、所得分配、經濟成長等因素，探討資本利得課稅在經濟 上的影響。第四章，探討資本利得稅有關的三個重要觀念－－資本利得額、實現率、 有效稅率。第五章，就我國行資本利得課稅制度加以詳盡分析與檢討。第六章，本文 結論及建議的提出。另外，附錄一則，利用各種數學上的證明，驗證Jerry R. Green 及Eytan Sheshinski兩位教授所提出的各種最適資本利得課稅方法的可行性。

創業天使(business angel)是一種新興的融資管道。以往創新產業利用創投事業募集創業基金，進行投資的工作。近年來創投的生態漸漸改變，除了資金挹注集中在營運中後期，創投事業也不再扮演提供管理諮詢的關鍵者角色。這時，創業天使的出現，不僅解決創業公司種子期資金不足的窘境，且積極涉入公司經營、提供產業諮詢，以增加企業的附加價值。 以往創投事業及創業公司的文獻中，僅就資本利得稅對雙方的投入影響作討論。而Elitzur and Gavious(2003)則試著加入創業天使的角色，利用三方模型衡量創業天使的加入能否對創投與創業公司間因道德危機問題產生的無效率有所改善。 本文以Elitzur and Gavious(2003)文章為基礎，加入政府的租稅政策，藉以衡量政府的介入是否對三方的投入有所助益。本文研究結果發現，只要政府課徵資本利得稅，將會使三方的投入水準減低；即使採取預算平衡的租稅政策，仍無法改變投入無效率以及創新產業收入過低的情況。因此，在現實社會中，政府不應課過重的資本利得稅，以期能使整個產業營收增加。如果採取對創投事業及創業天使資本利得補貼並搭配對投資之課稅，政府的原意乃是提高各行為參與者之資本利得，以增進效率水準；然而因課稅的過程中產生誘因降低的情況，最終反而會使三方的資本利得減少。唯有對單一參與者個別給予資本利得補貼並搭配課徵對誘因沒有影響的總額進入稅，才會使整個計畫的利得增加，達到有效率的投資水準。是故，政府的租稅政策對創業天使、創投事業及創業公司三者並不一定會達到較有效率的結果。

無 / This study establishes a model of the stock market involving the rational speculators to investigate whether the imposition of tax on capital gains can reduce the market volatility. The finding is that the effect of tax on the stock price volatility varies according to the types of shocks hitting the market. In the cases of the issuing shock and the dividend shock, raising the tax rate could be a way to stabilize the stock market. On the contrary, when the margin-rate shock occurs, it tends to magnify the effect of the shock and therefore increases the market volatility. Thus, it could be concluded that an increase in the tax rate may increase or decrease the stock price volatility depending on the type of unexpected shocks.

本文以Sandmo引進勞動供給的租稅逃漏模型為基礎，以是否具有其他所得來區別社會上的富人或窮人，富人可以在勞動市場中投入勞動供給賺取勤勞所得，或是將勞動供給投注在以其他所得做投資的投資行為上，賺取資本利得；但是窮人只能將其勞動供給投注在勞動市場中賺取勤勞所得，在雙方決定勞動供給以追求效用極大化下，可決定彼此的所得差距。 由於所得稅具有所得重分配的功能，因此我們首先比較在不同所得稅制下的所得差距，以得知所得稅是否達成其重分配功能。結果是：僅課徵勤勞所得稅時的所得差距會大於未課稅時的所得差距，勤勞所得稅反而使所得情形惡化，因為富人可藉由移轉勞動供給的方式規避稅負；而同時課徵勤勞所得稅及資本利得稅後之所得差距會小於僅課徵勤勞所得稅時的所得差距，代表資本利得稅可有效改善所得分配惡化的現象。 政府除了可以用所得稅的手段改善所得分配外，也可以以移轉性支出的方式達到相同目的。第一個情況是假設目前僅課徵勤勞所得稅，所得差距情形惡化，當政府決定將全國所收取的勤勞所得稅做為移轉性支出平均分發給窮人時，會得到不一定可以改善所得差距惡化現象的結果，必須視窮人對消費和休閒的替代彈性，以及替代效果與所得效果的大小而定。第二個情況是假設目前同時課徵勤勞所得稅及資本利得稅，並以富人所支付的資本利得稅做為移轉性支出平均分發給窮人，此時的移轉性支出能夠進一步改善所得差距惡化的情形。由以上兩段可知，若政府要有效地改善所得差距惡化的情形，最好的辦法是課徵資本利得稅，並將資本利得稅做為移轉性支出的財源。 / In this paper we use a Sandmo’s (1981) type tax evasion model to discuss the effects of proportional income taxation on income distribution among the riches and the poor. The riches are different from the poor in that only the former have exogenous income which can be invested to obtain capital gains. Therefore, while the riches choose between allocating their time to make labor income or to make capital gains, the poor can only attribute their time to making labor income. The tax system treats labor income and capital gains differently. The income distribution among the riches and the poor is determined by the difference in total incomes. We first show that when only labor incomes are taxed, the income tax worsens the income distribution as compared to the income distribution when there is no income tax. In other words, an income tax system with preferential treatments on capital gains is detrimental to income distribution. This result is intuitive because the riches can switch their labor supply from making labor income to making capital gains for tax avoidance, while the poor do not get to do so. An income tax system is beneficial to income distribution when capital gains are taxed at the same rate as labor income. Second we discuss the role of income transfer program on the income distribution and show that if the government uses labor income tax as the only financial source for the transfer, the effect of such income transfers on income distribution is ambiguous. It is decided by the magnitude of the elasticity of substitution between consumption and leisure, and the net effect of the substitution and the income effects. To improve income distribution, the best scenario is to use tax revenues from capital gains as the financial source of income transfer.

我國在民國102年復徵證券交易所得稅，其本質屬於資本利得稅，本文欲探究資本利得稅對資產選擇之影響，再進一步將閉鎖效果納入資產選擇模型，討論課稅實現原則下，資本利得稅的稅率對資產選擇的影響。 本文假設兩項資產，分別為無風險性資產與風險性資產，發現在資本利得稅、資本損失可完全扣抵的情況下，政府擔任分散風險的角色，財富的風險性下跌，代表性個人增加風險性資產持有份額。納入閉鎖效果討論課徵資本利得稅下的資產選擇，設立兩期模型，代表性個人分配財富於無風險資產與風險性資產。若要代表性個人在第二期轉換投資組合，則代表性個人將要求新投資組合之報酬高於原資產之報酬加上處分原資產所產生之資本利得稅，而代表性個人可透過改變風險性資產持有比例調整新資產組合之報酬。研究發現，新投資組合的風險性資產持有比例受到原資產之資本利得稅率影響，原資產的稅率越高，則新投資組合的風險性資產持有比例越大，主因稅率越高，閉鎖效果的強度越強，因此若代表性個人要轉換資產的話，可透過增加風險性資產持有比例來增加新投資組合的預期報酬，亦表示代表性個人之風險承擔意願增加。

本研究嘗試就資本利得是否為經濟學上的所得、是否為稅法上的課稅所得及世界各國稅制上對資本利得之對待等三方面加以剖析與說明。 首先，經濟學上國民所得之概念，產出當等於所得，此為供給面與需求面恆等式。因此在證券市場買賣證券，只是屬於所有權的移轉而已，對產出沒有影響，意味著所得沒有增加，故資本利得非為經濟學上所稱之所得。 其次，在文獻回顧上，提供英國、德國及美國學者在時間沙河過程中，探求應納稅所得額概念之思想形成的脈絡足跡，且歸納「泉源週期說」、「勞務流通說」及「淨資產增加說」三種稅法上的所得定義主流學說。資本利得不具規則性及重發性而排除於「泉源週期說」課稅所得中；非消費能力的表現亦不為「勞務流通說」所接受不將其視為所得；唯獨「淨資產增加說」的所得概念包括了已實現及未實現的所得額總和。 第三，本文研究世界各國對資本利得之租稅處理，包括英國、美國、新加坡、香港及澳大利亞等五個國家。香港及新加坡基於特殊目的，給予具有鼓勵性質之免稅措施。英國採分類所得稅制單獨課徵，而美國及澳大利亞則併入個人綜合所得稅中徵收。各國對資本利得不僅只就已實現之利得課徵，而且大多採取輕稅簡政的措施。

第一篇論述討論處置效果於選擇權市場的實證。處置效果係指投資人在處分資產時，傾向盡快賣出有未實現利得的投資部位，並且繼續持有有未實現損失的投資部位的行為偏誤現象。文獻上有關處置效果的實證多半集中在股票市場而少有於選擇權市場的實證。選擇權市場一般認為是具有私有資訊及較具備金融知識與經驗的投資人會選擇交易的市場。本文實證處置效果在指數選擇權市場上的影響。我們認為對於選擇權投資人來說，價內外程度是最重要且顯而易見的資訊，是很直觀可以衡量可能利得及損失的參考點。相較於傳統衡量根據過去交易價格所形成的未實現損益指標，價內外程度更能吸引投資人的注意力。以本文所提出的基於價內外程度衡量之賣出傾向指標(Moneyness-based Propensity to Sell, MPS)以及根據Grinblatt and Han (2005)所形成的調整後未實現資本利得指標(adjusted Capital Gains Overhang, ACGO)，每周將買權(賣權)排序成五等分後，我們發現持有最高等分的MPS或ACGO的買權(賣權)並賣出最低等分的買權(賣權)所形成的投資組合能夠產生超額報酬，顯示處置效果在指數選擇權市場亦存在。利用雙重排序(double sorting)的方法，我們發現MPS相較於ACGO，是較能夠在選擇權市場捕捉處置效果的指標。第二篇論述討論相似度衡量策略在期貨市場獲利的可能性。文獻上對於技術交易是否能產生顯著的報酬結果並不一致，然而實務上分析過去的價格走勢並使用技術指標所產生的訊號，是廣泛被接受的。現有測試技術交易指標獲利能力的文獻，通常假設投資人在實證測試的樣本期間一致性的參考某個交易指標產生的交易訊號並依此交易。然而實務上投資人可能同時參考不同的交易指標，每次交易可能根據不同交易指標所產生的訊號，且投資人會從歷史交易價格走勢中尋找類似於現有走勢的狀況，以這些歷史走勢接續的報酬率做為現有走勢未來報酬率的預期值。本文中我們提出一個較符合實際狀況的決策過程來描述技術交易投資人的行為，並重新檢視技術交易的獲利能力。我們提出的決策過程包含三個步驟。首先投資人建立一個特徵向量，包含投資人所認為足以預測未來報酬率並足以描述現況的指標。第二個步驟，投資人從過去某段期間中尋找相似於現有特徵向量的歷史狀況，並以這些歷史狀況接續的報酬率來作為預測的根據。最後，投資人依照過去的歷史狀況與現在有多相似，作為接續報酬率的加權權重，並以相似度權重加權平均報酬來做為未來報酬率的預測值，我們將依照相似度加權報酬所產生交易訊號所形成的策略稱為相似度衡量交易策略(Similarity-based trading rules)。我們檢視相似度衡量交易策略在九個不同的期貨市場中的獲利能力，在考量data-snooping及交易成本後，每日相似度衡量交易策略仍在其中六個市場中獲得顯著的報酬率。 / The disposition effect, which refers to the tendency of investors to selling their winning investments too soon and to hold losing investments too long, has been well-documented in the extant literature. However, while empirical researches focus on examining the behavioral bias in the stock market, little attention is paid to the option market, where most informed investors and sophisticated traders gather. This essay tests for the disposition effect on the index options market. We argue that moneyness, the most salient and readily available information for option investors, is a natural reference point for potential gains and losses, which likely attracts market participants’ attention more than traditional measures that are based on past trading prices. Based on the Moneyness-based Propensity to Sell (MPS) measure that we introduce and an adjusted capital gains overhang (ACGO) measure of Grinblatt and Han (2005), we find that a strategy formed by buying calls/puts in the highest MPS or ACGO quintile and selling those in the lowest quintile would generate significant abnormal returns, suggesting the presence of the disposition effect. Using double sorting method, we find that the MPS is better as a measure in capturing the disposition effect on the options market than the ACGO. While the literature documents mixed results for the profitability of technical trading rules, the use of technical buy/sell signals based on analyzing past prices is widely accepted by practitioners. The existing literature on testing the predictive ability of technical trading mostly assumes that a technical investor consistently makes investment decisions based on the buy/sell signals according to one particular trading rule during the entire sample period. However this may be far from reality. Technical investors may simultaneously make predictions based on different technical indicators and follow different technical signals. Furthermore, they analyze historical price patterns that are similar to the current market condition and make assessment of future returns based on the subsequent returns of these similar patterns. The process is known as charting. We attempt to propose a more realistic decision-making process that incorporates the similarity-based predictors to account for technical investors’ decisions in the real world and reexamine the profitability of technical trading rules. The proposed process includes three steps. First, the investor attempts to predict future returns based on a vector of current characteristics that is sufficient for his assessment of the future returns and to depict the present scenario of the stock market. Second, the investor searches for the similar patterns in a specific time window prior to the current date and make an assessment of the future returns based on how similar these past patterns and the current pattern are and how rewarding the subsequent returns of the similar patterns are. Third, the investor is assumed to form a similarity-based indicator which is an assessment of the future returns depended on the similarity-weighted average of all previously observed values of the subsequent returns. The technical investor is then assumed to buy/sell according to the signals generated by the similarity-based trading rules (SBTR). We examine the profitability of the SBTR in nine futures markets and find significantly positive and robust returns after considering the data-snooping adjustments and transaction costs in six of the nine markets.