Abstract
The principle of proportionality plays a key role in shaping the principles of the tax law system, as it is an important element in the protection of taxpayer’s rights. The interpretation directive related to the principle of proportionality has a doctrinal, normative, and jurisprudential character. It is an EU and constitutional standard and should become a rule used on a daily basis in the practice of tax authorities. As a general principle of tax law, it is addressed to the legislative, executive, and judicial authorities. The article analyses the case law of the CJEU, the Constitutional Tribunal and the Supreme Administrative Court, which leads to the following conclusions. The CJEU quite often refers to the principle of proportionality in its jurisprudence and has developed a jurisprudence doctrine based on the doctrine of law. The Constitutional Tribunal, although in a limited scope, also employs the principle of proportionality. In disputes between tax authorities and taxpayers, Polish administrative courts apply the principle of proportionality using a pro-EU and pro-constitutional interpretation.