It is often said that the tax system of Navarre is harmonized with that of the State, that the agreement Economic harmonizes the taxes of Navarre or, in short, that Navarre has harmonized taxes. All these expressions revolve around a term that is attractive due to the synthesis of union and difference that it entails, of balance and mutual respect..., projected on the relations between Navarre and the State in subject tributary. Unfortunately, however, we are dealing with an expression that has a well-defined nature, a clearly defined and rooted meaning, which has nothing to do with the use that is made of it in the foral regime.

To speak of harmonized taxes or, in general, of tax harmonization within the European Union, points to the existence of a series of taxes - not all of them - whose fundamental structure is regulated by the committee of the European Union. The realization of the Community Market does not require, of course, ceding to the EU the exercise of competences in subject taxation. However, sometimes a Community rule is necessary to remove tax obstacles to the functioning of the market or to avoid distortions. In view of the zeal that the States keep with regard to everything that concerns this subject, tax harmonization is opening the way as a formula, not of unification but of approximation of national legislations.

Since the origins of the EEC, tax harmonization has focused on indirect taxation, mainly because of the close relationship of these taxes with the price of goods and services and, therefore, with the consequent risk of market distortion. In fact, VAT and Excise Duties are nowadays strongly harmonized taxes (including taxes on the raising of capital), to the extent that VAT is often considered a Community tax. On the other hand, direct taxes are not harmonized, apart from some very specific aspects within the field of corporate taxation and the action of the Court of Justice of the European Union as a negative legislator - similar to the Constitutional Court - when it examines national legislations in the light of Community freedoms (freedom of establishment, freedom of movement of persons, goods, services and capital) and the prohibition of State aid established by the Treaty on the Functioning of the European Union.

It is not necessary to insist more to realize that none of this has anything to do with the system of agreement Economic. Personal Income Tax, Corporate Income Tax, IS and ISD are expressly contemplated in the agreement and, nevertheless, they are not harmonized taxes. On the other hand, VAT and Excise Duties are harmonized taxes, not because they are provided for in the agreement, but because their basic structure is adapted to the provisions of the Community Directives. When, from the foral perspective of Navarre-State relations, we speak of harmonized taxes, what we are really trying to emphasize is that Navarre's taxes are articulated with those of the State, without any other implications. That is why it is much more accurate to use this expression, articulated taxes, to refer to the reality of the system of agreement. In the end, experience shows that resorting to expressions already coined or related to others that carry a certain legal baggage entails the serious risk that clearly differentiated realities end up being confused. It is enough to recall, in this sense, how the term "agreed taxes", used to refer to the taxes contemplated in the agreement and a transcription of the term "agreed taxes" originally used in the Basque regime, has led the Constitutional Court to erroneously confuse the fiscal reality of Navarre with that of the Historical Territories.