This article describes the different taxation systems regarding the entry of commercial ships into the ports of the North-Adriatic countries (namely Italy, Slovenia, Croatia). The taxes taken into consideration are largely known as light dues (or occasionally anchorage dues) and are based on the vessel, irrespective of the cargo discharged at the port and of any actual provision of “specific services”. In the above-mentioned countries, such taxes are based on different definitions and calculation models, in some instances taking the form of light dues, and are a clearly identifiable component (and, therefore, at least partly comparable) of the overall port-use costs charged to business operators. The geographical setting of the North Adriatic includes an international port range (mainly the ports of Trieste, Koper and Rijeka) competing in a partially overlapping hinterland, although differently. The drafting of an updated review of the tax component has become an interesting way to contribute, although through the analysis of a very specific and partial element, to the overarching research on competition in the North Adriatic ports and the role played by the diversity of political, legal as well as economic systems in an area which, in recent years, has on the whole recorded good traffic dynamics, as is to be expected from the hinterlands of Central and Eastern Europe.