The graduation thesis deals with the communal infrastructure construction on building land in the municipalities of Izola and Piran. In the first part, selected municipal detailed spatial plans and belonging programmes of supplying services to building land are presented. Furthermore, methods and criteria of calculating building land development fee are analysed within selected programmes of supplying services to building land. The costs of building a new communal infrastructure and the costs of existing communal infrastructure are discussed in the thesis as well as well as the ratio between them. The amount of the building land development fee has also an impact on the decision of potential investor on the investment project.