Environmental taxes, including energy taxes, are applied in all EU Member States. They are considered important instruments in the implementation of the EU energy and climate policies. The main purpose of the research presented in this article is to identify trends in the EU Member States in shaping environmental tax revenues, with particular emphasis on their most important group, i.e., energy taxes. The researchers sought answers to the research question regarding the existence of converging trends in this respect. The “letter values” method was used in the research procedure, which is an extension of the box-plots method. The analysis covered 27 EU Member States. The data used in the research came from the Eurostat database (2009–2020). As a result of the research, it was found that in the EU as a whole, there is a slight downward trend in the share of environmental tax revenues in GDP and the share of environmental tax revenues in total tax revenues, while the share of energy tax revenues in total environmental tax revenues shows a slight upward trend. The decomposition of the research and the conducted comparative analysis, including the determination of specific rankings, showed that both the level and trends in the shaping of the studied variables vary considerably in the individual EU Member States.

Purpose: The objective of this paper is to identify, with the use of statistical methods, the relationship between the level of fiscalism and the ratio of social expenditure to the total public expenditure in the EU-28. Design/Methodology/Approach: Linear regression and correlation were used to assess the interdependence between the tax revenue-to-GDP ratio and the ratio of social expenditure to the total public expenditure in the EU-28. Then, using the direction of the slope as the criterion, the EU 28 were classified into countries with a positive relationship (the lower and upper border of the confidence interval are positive) and countries with a negative relationship (the lower and upper border of the confidence interval are negative). Findings: The research confirmed that the EU Member States with a high level of fiscalism in 2004-2018, in principle, were characterised by the following interdependence: the higher the tax revenue-to-GDP ratio was, the higher the ratio of social expenditure to the total public expenditure was. After the decomposition of public expenditure, a similar relationship was identified for public expenditure on social protection, while no such relationship was identified for other categories of expenditure for social purposes. Practical Implications: The research results are important as the EU-28 are striving to maintain fiscal stability. The research findings point to the need of verifying the tasks in the field of social protection in countries with a high level of fiscalism. Increasing these tasks, mean a further increase in the tax burden on the economy. Originality/Value: The research adds value to the testing of the fiscal-synchronization hypothesis. The originality of the research mainly results from its detailed nature. The relationship between the level of fiscalism and public expenditure was identified not in general terms but incurred for tasks related to the implementation of social policy in the individual EU-28.