隨我國經濟發展與產業結構變遷，從經濟管制到市場自由，自勞力密集之製造出口至技術密集之產業升級，期間有不同階段之稅捐優惠作為引導。 研究發展活動具有外部正面性，同時有市場失靈之可能，私部門可能因此而不願投入、或投入不足之資源，進行研究發展活動。為獲得整體社會之最大利益，稅捐除作為財政工具，作為經濟目的之政策誘因之正當性也獲得承認。政府為促進民間投入研究發展，可能以直接補貼或提供租稅優惠方式給與鼓勵，以協助企業進行研究發展，降低跨足新興產業之進入障礙及營運風險。 但稅捐優惠之提供，乃對具相同負擔稅捐能力者，課以不同之稅捐負擔，以引導特定之作為或不作為，無可避免的違反量能課稅原則下的平等原則。何以相同負擔稅捐能力者，有不同之稅捐負擔，應有實質之說明理由。其成效與影響如何，是否達成制度上犧牲量能課稅原則所欲追求之目的，應與直接補貼接受相同程度之公開之監督與績效衡量。 就研究發展投資支出可抵減之稅額，未分配盈餘加徵百分之十部份乃為縮減營利事業所得稅與個人綜合所得稅之之實現時間差距，而研究發展投資抵減，則為分擔企業研發風險，鼓勵知識之累積，提升附加價值，兩者制定之精神互不相同，以研究發展投資抵減未分配盈餘加徵百分之十之「營利事業所得稅」，似有扞格，但兩稅合一後，營利事業所得稅在公司此一法律主體之稅捐負擔意涵已大幅下降。是以，就研究發展投資抵減未分配盈餘加徵百分之十之稅額部分，衝突程度亦獲得一定程度之解決。另外，所得基本稅額條例規定營利事業及個人皆需有一定之基本稅額負擔，此即所謂最低稅負制。所得基本稅額條例明確將研究發展投資抵減之金額計入營利事業基本稅額之計算，對之課以基本稅額，符合所得基本稅額條例施行之精神，乃合理之設計。 本文以表格方式整理方式，對照獎勵投資條例、促進產業升級條例與產業創新條例對稅基、稅率、稅額與時間歸屬之影響；針對投資抵減實務施行爭議，本研究則整理相關判決以供參考。 以上述三條例之演進趨勢而言，稅捐優惠之給予範圍已逐漸縮小，而改以直接補助或金融協助；技術開發補助與輔導；提供資訊管道、建構交易平台、整合業界、規劃工業區等行政協助，應用多元方式協助產業發展。 研究發展投資抵減之適用範圍、申請期限、申請程序、核定機關、施行期限、抵減率及其他相關實體事項，若立法之技術與資源已有相當累積，以法律位階就投資抵減作較具體之規範，應為立法機關所考慮。 / Abstract With the economic development and the changing in industry structure, from economic regulation to an open market, and from labor-intensive to technology -intensive, the government is guiding the market by tax incentive and other kinds of tool. Because R&D has positive externalities, barriers to entry and the possibilities of market failure, private sector may not willing to input resource for R&D. For social welfare maximization, the government may use tax incentive to encourage private sector to do R&D. By provide R&D Tax Credit or subsidy , the government can encourage the private sector to do more R&D. But providing tax credit will unavoidably conflict with Principle of Ability to Pay. There should be a reason for why people have the same ability to pay the tax pay different tax. The same supervise and performance evaluation must be done for tax credit and subsidy. For 10% surtax on Retained Earnings is to narrow down the time difference between the realized of corporation tax and individual income tax, and the R&D credit is for sharing risk of failure, encouraging research and development, and rising EVA, the tax which can be credited should not include surtax on Retained Earnings. But with the applying of Integrated income tax system, the conflict has been partly solved. For Alternative Minimum Tax, R&D expense can’t be credited is a reasonable design. This paper mainly focus on comparing the differences of tax base, tax rate, and income tax payable etc. in the Enactment of Encouragement Investment, the Statute for Upgrading Industry, and the Statute for Industrial Innovation. Also sued cases were collected to report any violations of existing R&D policies for future amendment concerns. The range of tax credit is shrinking, and is replaced by subsidies, industrial technology development programs, and the setting of science parks etc. And for principle of taxation under the law, The Statute for Industrial Innovation should be ruled in law by the legislative.