Abstract: The deduction right, as the core right of a taxpayerof value-added tax, can play a better role in the double function of the restriction of the state's taxing power and the protection of the rights and interests of taxpayers only if it gets rid of the“right”claim that is difficult to determine from the moral level and is confirmed as a real positive law right. Then it can guide the optimization of the value-added tax system and leverage the practical difficulties of the value-added tax law. This identity conversion can be accomplished through the internal justification of the rights. Although the internal justification of the right of deduction is based on the inherent reasons of the right, the process is intended to describe the dynamic process of how the right obtains this qualification from the environment in which it is located. The connecting bridge between the rights and the external environment should be built with the help of the evaluation. Therefore, the argumentation process consists of two core structures: the ontology and the reference. On the one hand, it evaluates the right itself, describing its legitimacy and importance; on the other hand, it evaluates the internal-external interaction, showing the legitimacy and importance of deduction right to the external environment. In a word, on the one hand, we should start from the basic legal theory of rights to demonstrate the built-in mechanism of the deduction right conforming to the right; on the other hand, we should conduct standardized investigation to justify the legal character of the deduction right being abided by the law of VAT.

Key words: deduction right, value-added tax, internal justification, emerging rights