Recently, there has been a growing interest in studying the determinants of budget realization both in other countries and regions, as well as in the Republic of Croatia. The aim of this thesis was to determine what could be the determinants of budget realization and what their influence is. Using evidence from various works on data from other countries such as Macedonia and Poland, hypotheses were formed and tested on data for the Republic of Croatia. The first hypothesis seeks to determine whether local units with higher budget revenues have higher capital expenditures, higher wage expenditures, and higher budget transparency. The goal of the second hypothesis is to determine whether the size of the population has a positive effect on the total tax revenues of the local unit. The third hypothesis aims to examine whether there is a statistically significant positive relationship between income and capital aid to the budget and budget expenditures of the local unit, and whether there is a statistically significant negative relationship between population density and budget expenditures of the local unit. The fourth hypothesis states that local units with greater budget transparency have higher budget expenditures. The fifth hypothesis aims to determine whether a higher budget income of a local unit means a lower probability of a budget deficit. It also examines whether it is true that the greater the number of companies and the workforce, the greater the chances of achieving a budget deficit. Before testing the hypotheses, graphs of dependent and independent variables were drawn, and relations were observed, with the help of which the results of formal testing can be easily assumed. It was concluded that the higher the expenditures for salaries per inhabitant, the higher the budget revenues per inhabitant in counties, cities and municipalities. Also, in all local units and counties, the larger the number of inhabitants, the higher the total tax revenues. The higher the capital aid to the budget per inhabitant, the higher the budget expenditure per inhabitant also in all counties, cities and municipalities. In the end, it was concluded that in all local units and counties, higher population density means lower budget expenditures per inhabitant. The last chapter of the thesis is dedicated to testing the hypotheses that gave the following results: It was shown that counties with higher budget revenues have higher capital expenditures, while cities and municipalities that have not only higher capital expenditures but also higher expenditures for salaries have higher budget revenues. As for tax revenues, it was shown that all local units and counties with a larger number of inhabitants have higher total tax revenues. Also, it was shown that counties with larger capital grants to the budget have larger budget expenditures. Cities with higher capital grants to the budget and higher income have higher budget expenditures. The same statement was shown for municipalities, but it is also true that municipalities with a higher population density have lower budget expenditures. In the end, it turned out that as budget expenditures grow in cities and municipalities, so does the probability of a budget deficit. The conclusions of this thesis can be refined, the hypotheses could be tested on all local units together, and various new independent variables could be added to the hypotheses. The presented tests and results can help to make better predictions of the budget in the coming year and, therefore, to make better use of it.