REMCO (Network for the Study of Contemporary Monarchies) has published an interesting report entitled «The Cost of Heads of State in Europe: A Comparative Analysis of Monarchies and Republics».

It offers a comparative analysis of European Monarchies and Republics based on official budget data and homogeneous macroeconomic magnitudes. Specifically, it will compare the Head of State of Spain with those of the United Kingdom, Denmark, Norway, Italy, Germany and Portugal, evaluating the absolute expenditure and its relative impact in relation to population, GDP and public spending.

Here is the link; the report is available in PDF format.
https://remco.es/2026/03/03/el-coste-de-las-monarquias-y-republicas-europeas/