稅捐稽徵法第28條第2項乃要求稅捐稽徵機關於自知有錯誤原因之日起二年內必須查明錯誤，將溢繳稅款退還給納稅義務人，並且退還之稅款不以五年內溢繳者為限。該新規定雖然更為保障納稅義務人的權益，但其應如何具體適用仍有相當多值得討論之處。尤其是稅捐稽徵機關為溢繳稅款的退還時，應如何解決原先課稅處分形式存續力的問題。以及倘若納稅義務人對課稅處分不服而提請行政訴訟，並且該爭議已經行政法院判決確定，納稅義務人是否仍可以事後依稅捐稽徵法第28條第2項請求稅捐稽徵機關退還溢繳稅款？最後若稅捐稽徵機關在兩年內仍不查明退還，其不作為的方式，實務應如何加以應對？上述問題將在本文中參考德國及日本的實務以及學說見解，提出個人的改善建議。

Pursuant to the revised provision of sec. 28 para. 2 Taiwanese Tax Collection Act the Tax Collection Authority shall in the event that a taxpayer has made overpayment of any tax as a result of misapplication of tax law or miscalculation by the tax collection authorities or other mistakes that can be attributed to relevant government agencies, refund the overpaid tax within two years from the date the mistake was found out, and the period of refundable overpayment of tax is not restricted to within five years from such date. Although the revised law improves the legal protection of taxpayers and their interests, several aspects concerning the application of the revised law still need particular attention. Notable issues are inter alia how to deal with and/or how to overcome and adjust the binding effect of a prior tax assessment act, whether tax refund according to the new sec. 28 para. 2 Taiwanese Tax Collection Act can be claimed even still despite of the fact that tax assessment was subject of administrative litigation already before and what legal remedies are available to the taxpayer if the tax collection authority does not comply with its new obligation under sec 28 para 2 in a timely manner. The article analyses the aforementioned issues, thereby reference is made to German and Japanese law and proposes several amendments.