The aim of the article is to characterise selected tax principles included in the Polish financial law literature. Legal academics and commentators widely emphasise that these principles are extremely crucial for the tax system. They express the postulates to which a properly designed tax, as well as a rational tax system, should correspond. In view of the fact that the academic discourse has been emphasising for many years that tax law is of low quality and thus difficult and costly to apply, as well as the low assessment of tax regulations enacted as part of the so-called Polish Deal, it was considered appropriate to remind the significance of the most important of these models, the content of which was expressed as tax principles.