The influence of the European Union on population migration is becoming an increasingly important issue and is particularly relevant in the context of the Republic of Croatia. This master's thesis examines how Croatia's EU membership affects the dynamics of population migration, focusing on the country's tax system as a key factor. Population migration is the process by which people move from one geographic area to another, either within the same country or across national borders. These migrations can include both internal and cross-border movements, whether in search of better job opportunities or better living conditions. The question of labor mobility became a central issue after EU accession. This paper analyzes how changes in the tax system of the Republic of Croatia have affected citizens' decisions to stay, emigrate or return. The Croatian tax system includes different types of taxes, such as income tax, corporate income tax, value added tax (VAT), property tax and many others. Each of these taxes serves a specific purpose and functions in a specific way. In addition, it is important to define the trend of "emigration of highly qualified workers to other EU countries, as they find better conditions and often higher salaries there. On average, countries such as Germany, Austria and Ireland offer the highest salaries, making them the most desirable destinations for emigration. The concept of the "tax wedge," which reflects the difference between gross and net wages, also plays an important role in defining salaries. All of these concepts have a significant impact on people's decisions regarding their migration behavior.