本研究旨在探討營所稅稅率調升對企業投資和研究發展支出的影響，以及不同企業投資方式下的反應差異。通過對台灣上市前100大企業在2015年至2020年期間的財務資料進行分析，研究利用多元迴歸模型和差異中差異(DID)模型，對三個具體的研究假說(H1a和H1b)進行了檢驗和評估。
研究結果顯示，營所稅稅率調升對企業的固定資產投資比例以及研發投資比例的影響均不顯著。具體而言，調升後企業在固定資產和研發領域的投資水平並未出現明顯下降或增加。即使對僅考慮研發支出的企業投資方式進行了分析，其研發活動也未受到顯著影響，表明營所稅稅率調升對企業的研發投資影響有限。
這些結果可能反映了企業對營所稅稅率調升的適應策略。企業可能通過降低其他成本、調整業務結構等方式來應對政策變化，從而減緩對投資和研發支出的影響。此外，企業可能會尋求其他投資渠道或提高效率，以彌補稅率調升帶來的壓力。

This study aims to investigate the effects of corporate income tax rate increase on corporate investment and research and development(R&D)expenditure, as well as the differential responses under different investment strategies. By analyzing the financial data of the top 100 listed companies in Taiwan from 2015 to 2020, this research employs multiple regression models and difference-in-differences(DID)models to examine and evaluate three specific hypotheses(H1a, and H1b).
The results indicate that the increase in corporate income tax rate has no significant impact on the proportion of fixed asset investment or R&D investment by corporations. Specifically, post-adjustment, there was no significant increase or decrease in corporate investment levels in fixed assets or R&D activities. Even when analyzing the investment strategies focusing solely on R&D expenditure, the impact on R&D activities remained insignificant, suggesting a limited influence of the corporate income tax rate increase on R&D investment by corporations.
These findings may reflect corporations' adaptive strategies in response to the increase in corporate income tax rate. Corporations may mitigate the impact on investment and R&D expenditure by reducing other costs, adjusting business structures, or seeking alternative investment channels to compensate for the pressure brought about by the tax rate adjustment.

目錄
謝辭	i
中文摘要	ii
英文摘要	iii
目錄	iv
圖目錄	vi
表目錄	vii
第一章 緒論	1
第一節 研究背景與動機	1
第二節 研究目的	3
第三節 研究流程與架構	3
第二章 文獻探討	5
第一節 國內稅務新法規	5
第二節 投資決策與企業行為	7
第三節 稅收與盈利管理	13
第三章 研究方法	18
第一節 研究假說	18
第二節 實證模型與變數定義	18
第三節 資料來源與樣本篩選	21
第四章 統計分析與實證結果	23
第一節 敘述統計	23
第二節 共線性檢定	24
第三節 迴歸分析	28
第四節 電子業與非電子業的比較	32
第五章 結論與建議	36
第一節 研究結論	36
第二節 研究限制	36
第三節 研究建議	37
參考文獻	39
中文文獻	39
英文文獻	40

圖目錄
圖1‑1　研究流程圖	4

表目錄
表1-1　兩稅合一稅制變動比較	3
表2‑1　2018稅改有關營利事業所得稅稅率調整	5
表2‑2　投資決策與企業行為文獻整理	11
表2‑3　稅收與盈利管理文獻整理	16
表4‑1　敘述統計結果	24
表4‑2　Belsley-Kuh-Welsch(BKW)共線性診斷結果(INVa)	26
表4‑3　相關係數(INVa)	26
表4‑4　Belsley-Kuh-Welsch(BKW)共線性診斷結果(RD)	28
表4‑5　相關係數(RD)	28
表4‑6　迴歸分析結果(INVa)與DID模型結果	30
表4‑7　迴歸分析結果(RD)與DID模型結果	32
表4-8　營所稅調升對電子業與非電子業投資效果(INVb)的比較	33
表4-9　預期方向	34

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