조세소송상 처분사유의 추가·변경 - 가산세 부과처분을 중심으로 -

This article discusses the issue of supplementation or modification of the grounds for an administrative disposition in tax litigation, with a particular focus on cases involving additional tax assessments. First, supplementation or modification of the grounds for an additional tax disposition is permissible only to the extent that it does not alter the identity of the disposition; each such disposition constitutes a single tax unit and a single cause of action. Second, according to Supreme Court decisions, each type of additional tax assessment corresponds to a separate taxable unit and thus to a distinct cause of action, which aligns with general principles regarding the modification of grounds for disposition in tax litigation. Third, supplementing or modifying the grounds of disposition by introducing a different type of additional tax constitutes a post hoc modification of the disposition itself, thereby altering its identity and changing the subject matter of the litigation, which is impermissible. Fourth, tax statutes also support this interpretation, as they often treat different types of additional taxes as separate dispositions; for example, under the Value-Added Tax Act, the penalties for failure to issue tax invoices and for issuing false invoices are distinct. Fifth, allowing the grounds for disposition to be modified from one type of additional tax to another may infringe upon the taxpayer’s right to a defense. Sixth, treating different types of additional taxes as if they were interchangeable or substitutable may violate the principle of legality in taxation, which includes the requirement that all elements of taxation be prescribed by law.