Abstract: In the practice of tax law interpretation, one may be often faced with two difficult choices of being “favorable to the national treasury” or being “favorable to taxpayers”. Based on the financial needs, such practice of interpretation is usually more biased toward the direction of being “favorable to the national treasury”. But as a kind of atypical obligation of public law similar to the standardized contract, the organ that has the right to interpret should also follow the principle of universality for interpretation of debt. Therefore, when being in a situation in which the tax law is not clear or the taxation facts are not clear, and there are more than two understandings, the “rule of unfavorable interpretation” should be adhered to, so as to give favorable interpretation to the receiver of the rules, that is, to uphold the pro-taxpayer position in the interpretation of tax law. However, the role of pro-taxpayer interpretation of tax law should still be assessed rationally and treated objectively; neither underestimation nor overestimation is acceptable. It is not allowed to use it without proper conditions, nor can it be used offside. Only when the interpretive object is interpreted in accordance with the “general understanding rules”, and no exact conclusion of the interpretation can be drawn, can the pro-taxpayer principle be adopted. Only in this way can it be possible to clarify the clues among the complicated results from different methods of interpretations and to find the “only positive solution” acceptable to all parties.

Key words: tax law interpretation; taxpayer; tax debt; standardized contract; unfavorable interpretation rule