Evaluation of motor vehicle tax in terms of legal security principle

The principle of legal certainty is a fundamental principle that enables individuals to act within a predictable and stable legal framework. This principle is particularly significant in areas such as tax law, which regulate individuals' financial obligations. This study examines the compliance of motor vehicle tax (MTV) practices in Turkey with the principle of legal certainty, identifies the issues arising in this context, and proposes solutions. In the first section, the theoretical framework of the principle of legal certainty is discussed, and its components (clarity, non-retroactivity, respect for vested rights, the prohibition of analogy, and legal stability) are analyzed in detail. The second section provides an analysis of MTV implementation in Turkey, examining aspects such as taxpayers, taxable subjects, taxable events, tax base, and exemptions. Additionally, a comparative analysis of MTV practices in the United States, France, Germany, and the United Kingdom is presented. The third section evaluates Turkey's MTV implementation in terms of legal certainty and conducts a comparative analysis with the selected countries. The findings of the study indicate that Turkey's MTV practices contain significant shortcomings in terms of legal certainty. In particular, frequent changes in tax rates, retroactive applications, and the disregard of environmental factors undermine legal certainty. Regarding the principle of clarity, the fact that tax rates are determined annually by the Council of Ministers makes it difficult for taxpayers to predict their future tax burdens. In terms of non-retroactivity, the retroactive increase in tax rates demonstrates a violation of this principle. With respect to the principle of respect for vested rights, frequent changes in tax rates and retroactive applications negatively affect individuals' existing legal positions. The comparative analysis with selected countries reveals that MTV practices in the United States, France, Germany, and the United Kingdom are more stable and predictable and that environmental factors are more extensively considered. Notably, these countries have adopted taxation models based on carbon emissions and encourage the use of environmentally friendly vehicles. In contrast, the absence of direct consideration of environmental factors in Turkey's MTV calculations hinders incentives for eco-friendly vehicle usage. In conclusion, to improve Turkey's motor vehicle tax practices in terms of legal certainty, it is recommended that tax rates be determined on a long-term basis, a taxation model that considers environmental factors be adopted, regulations aligned with the principle of non-retroactivity be implemented, and consistency in administrative practices be ensured. These recommendations are crucial for strengthening tax justice and the principles of the rule of law. Key Words: Motor Vehicle Tax, Legal Certainty, Taxation Principles, MTV Implementation