過去與企業避稅評價相關之文獻呈現正反不一的證據，因此本研究以美國1993年至2017年的上市公司為樣本，進一步將企業避稅拆分為正常避稅、異常激進避稅及異常保守避稅，分別檢視其與企業價值之間的關聯性。本研究預期企業適度從事避稅可以增加稅後現金流量，提升企業價值；然而企業避稅若異常激進，可能導致代理成本、稅務風險等額外成本的增加，而企業避稅若異常保守，亦會使企業無法保留足夠現金流量，引發投資不足等問題，因此企業從事異常激進或異常保守的避稅行為皆會降低其企業價值。實證結果發現企業正常避稅與企業價值呈顯著正相關，企業異常保守避稅與企業價值呈顯著負相關，且市場對高財務限制並從事異常保守避稅之企業給予較負面的評價，但沒有發現支持投資者對企業異常激進避稅給予負面評價的證據。總體而言，本研究結果表明投資者能夠辨別企業避稅是否超出合理範圍，並給予相對應的評價。

The prior literature shows that there is mixed evidence in the valuation of corporate tax avoidance. Therefore, this study decomposes corporate tax avoidance into normal, abnormal aggressive and abnormal conservative tax avoidance, and examines the relationship between them and firm value respectively, using a sample of public companies in the U.S. from 1993 to 2017. We expect that firms appropriately engage in tax avoidance can increase the after-tax cash flow and thus enhance firm value. However, abnormal aggressive tax avoidance may result in additional costs, such as agency cost and tax risk, while abnormal conservative tax avoidance may also make firms unable to retain sufficient cash flow and cause problems such as insufficient investment, so both of them will reduce firm value. The empirical results find that the normal tax avoidance is positively associated with firm value, abnormal conservative tax avoidance is negatively associated with firm value and investors gives more negative valuation to firms with high financial constraints and engaging in abnormal conservative tax avoidance, but find no evidence that abnormal aggressive tax avoidance is negatively associated with firm value. As a whole, our results show that investors can distinguish whether corporate tax avoidance is beyond the reasonable range and give corresponding valuation.

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