本研究以我國上市（櫃）公司89年至92年財務報表資訊及營利事業所得稅申報資料進行實證研究，探討造成我國財務會計所得與課稅所得差異之原因及財稅差異與企業評價之關係。在探討造成財稅差異原因方面，實證結果顯示除折舊費用未達統計上顯著水準外，呆帳費用、投資損失、存貨跌價損失及負債比率與財稅差異呈顯著負向關係，而投資利得、證券期貨交易所得、出售土地增益、企業規模、資產報酬率、電子業及營建業與財稅差異呈顯著正向關係。在探討財稅差異與企業評價之關係方面，本文援用Ohlson模型進行分析，結果發現財稅差異殘差項與股價呈正向關係，顯示投資人視未預期之財稅差異可能具有傳遞未來樂觀之財務會計所得或可節省稅負支出之租稅利益等資訊意涵因而反應於股價之上。依據實證結果，本文發現獲利能力越好或規模越大的公司越有可能透過租稅規劃，減少租稅上之負擔，此發現可作為稅務主管機關未來選案之參考；又本文也發現財稅差異具有資訊意涵，然現今財務報表揭露所得稅相關資訊有限，因此本研究建議證券主管機關應適度加強企業所得稅相關資訊之揭露與規範。 / Using 2000 to 2003 financial statement data and tax return data of listed and OTC companies in Taiwan, this study explores the sources of difference between tax income and financial reporting income and the relationships between book-tax differences and business valuation. The empirical results show that except for depreciation expense, bed debt expense, losses on investments, loss due to market decline of inventory, and financial leverage are negatively related with book-tax differences. However gains on investments, gains on securities transactions, gains in land transactions, business size, return on assets, the electronics industry, and the building industry are positively related with book-tax differences. The results also show that the regression residuals of book-tax differences are positively related with stock prices. This means that investors regard unexplained residuals as future earnings or income tax savings which are then reflected on the stock prices. The empirical results indicate that firms with greater profitability or large firms have greater incentives to conduct tax-planning which tend to reduce taxable income relative to income for financial reporting purposes. Our findings provide evidence for the Taxation Agency when doing audit adjustments and lend support for book-tax differences contain information that is relevant to firms’ valuation. However, in practice disclosure of information about income tax in financial statements is still limited, thus restricting investors in estimating book-tax differences. The security authority should devise appropriate accounting policies to improve disclosures on firms’ income tax information.