稅捐規避行為乃納稅義務人基於獲得租稅利益，違背稅法立法目的，濫用法律形式，規避租稅構成要件之該當，以達成與交易常規相當之經濟效果。基於租稅公平，納稅義務人不得以稅捐規劃權利為由，濫用權利從事稅捐規避。故我國有實質課稅原則，美國法上則有經濟實質原則等否定納稅義務人稅捐規避在稅法上之效果。但對於納稅者利用立法漏洞之稅捐規避行為，除否定其稅法上利益外，得否再施以處罰嚇阻之，則頗有爭議。美國經濟實質原則雖有處罰規定，但質疑聲音頗多。基於處罰明確性、有責主義，以及修補立法漏洞應是立法者之責任，本文認為單純的稅捐規避行為應不具有可罰性。

Because of the tax equity and fairness, taxpayer cannot abuse tax plan right to tax avoidance. To defend tax avoidance, Taiwan Congress codified the principle of substantive taxation. United States Congress codified the judicially created economic substance and business purpose doctrines. By the doctrines to fix the mistake of tax laws were literally. Should tax avoidance penalty provision be enacted to defend tax avoidance? Although United States Congress adds economic substance penalty. But a lot of scholars advocate the economic substance penalty should not have been enacted. Because of liability is basic principle of penalty, requirements of clarity of punishment in a rule-of-law nation. And Congress should legislate to correct tax mistakes but not penalty taxpayer. Thus tax avoidance penalty provision should not be enacted.