Prior to the implementation of FAS 142 in 2002, goodwill was amortized annually. Now, companies with goodwill on their books must test it annually for impairment. This paper examines the effectiveness of goodwill amortization and impairment of goodwill both before and after the adoption of FAS 142 by analyzing their effect on abnormal stock returns. My results regarding the effect of goodwill amortization on stock returns are inconsistent, suggesting that goodwill amortization is not useful in determining the value of a company. My results also suggest that the stock market anticipates goodwill impairments before they are announced.

「為利企業以併購進行組織調整，發揮企業經營效率」為企業併購法之立法目的，因此，第三章訂有許多租稅措施，以排除企業併購之租稅障礙。然而，實務上稅捐稽徵機關常以各種理由否准認列企業併購商譽攤銷費用，即便納稅義務人提起行政救濟，行政法院法官多認同稽徵機關主張，作出不利於納稅義務人之判決。雖最高行政法院已於100年12月份第1次庭長法官聯席會將相關爭議舉證責任的分配作出決議，此決議的合理性仍有探討空間。 本研究試圖以近三年企業併購商譽攤銷相關判決為研究範圍，首先，將實務爭議類型化，統計行政法院作出對納稅義務人不利判決之主要原因，並利用法令及財務會計準則相關規範，分析各類型判決；其次，探討前述最高行政法院100年決議內容是否合理；最後，以商譽的本質及企業併購經濟實質，提出個人建議，供後續研究及修法參考。 / “The Business Mergers and Acquisitions Law (the Law) is enacted to facilitate merger /consolidation and acquisition by a business for purposes of reorganization and optimal operation efficiency.” Therefore, there are some taxation measures which aim to get rid of obstacles in taxation during merger and acquisition in chapter 3 of Business Mergers and Acquisitions Act. However, in practice, the competent tax collection authorities usually use every argument to reject the recognition of the expense of goodwill amortization. Even that the tax-payers petition for administrative redresses, the result of judgments are often unfair to them. Although the Supreme Administrative Court rendered the resolution on the distribution of burden of proof in the first joint meeting of the President of the judges in December, 2011, the rationality of the resolution is open to question. This study takes judgments of goodwill on business mergers and acquisitions from the past three years as examples, and attempts to analyze and classify these controversies in practice into patterns. Besides, it discusses the rationality of the resolution in 2011. Last, to supply some references for the future researches and the amendments on the law, this study analyzes and provides perspectives on the goodwill generated by business mergers and acquisitions and the essence of goodwill itself.