稅法係以量能課稅原則作為建制原則,惟減免稅負之規定卻不必然符合量能課稅原則。減免稅捐之規定,其法律性質可分為兩種:量能課稅原則之具體化規定、稅捐優惠。倘若係為了引導納稅義務人從事某特定類型行為或不從事某種行為,以達成經濟政策、社會政策、環境政策等等財政收入外政策,其所依循之法律原則即已非量能課稅原則。系爭規定毋寧是以犧牲量能平等負擔來換取政策目的之達成,故性質上應被定性為稅捐優惠。反面來說,倘立法者係基於量能課稅原則而為稅捐減免規定,則該規定之法律性質即非稅捐優惠。 按司法院大法官解釋第648號解釋理由書意旨,財稅經濟領域方面之法規僅需採取寬鬆的違憲審查。本文對此並不完全認同。從案件類型或事務領域建構類型化審查理論固為提高憲法解釋之可預見性、法安定性以及減少司法恣意所必要,惟仍應避免發生過度簡化類型之情形。稅法案件與經濟法案件在法理上有極大的不同,故大法官不應將稅法案件與經濟法案件混為一談。經分析現有不同案件類型之大法官解釋後,本文認為平等權審查之違憲審查標準與違憲審查密度,除應整合德國與美國見解外,並宜加入其他原則以周全化違憲審查,使之符合案件類型之特性與法理。爰此,提出「目的與比例關聯性」之看法。此外,稅捐優惠之違憲審查,在審查密度部分,基本上經濟目的稅捐優惠之審查密度最高,其他公益目的稅捐優惠次之,社會目的稅捐優惠最低。
Tax law takes the ability-to-pay principle as its fundamental principle; however, not all tax relief provisions correspond to this principle. If the tax relief provisions are set up to guide the taxpayers to do, or not, to do certain behaviors to achieve some policies which are not for financial purpose, they are not based on ability-to-pay principle. Actually, the purpose of those provisions is to achieve some policy goals at the expense of equal tax burden, so they should be characterized as tax preference. On the opposite, if the tax relief provisions are based on ability-to-pay principle, the nature of these provisions will not be tax preference. According to the reasoning of J. Y. Interpretation No. 648, regulations on tax and economy only need to take loose judicial review; this dissertation does not entirely agree with this. We should avoid oversimplification although constructing theory of judicial review by classifying the case type or the area of affair is necessary to improve the predictability of constitutional interpretation, legal stability and to reduce judicial indulgence. Therefore Justices should not confuse tax law cases with economical law cases since there is a great difference between them in jurisprudence. After analyzing the different case types of J. Y. Interpretations, this dissertation asserts the standard and density of scrutiny to the equal right should not only integrate Germanic and American view, but join other principles to make judicial review more complete and in line with the characteristics and jurisprudence of different case types. For the reason, this dissertation proposes a view: “purpose and proportionate relationship”. Furthermore, in the order of the density of scrutiny of judicial review to tax preference basically, tax preference for economical purpose should be have the highest density of scrutiny, tax preference for other public interest purposes has the second, and tax preference for social purpose has the least.