Fiscal decentralization has been a worldwide trend in the last decades, especially in Europe and in Latin America. This process, however, have not been uniform in all countries, acquiring different forms in different countries and within a same country over the years; those processes even involved not only federal states, but also traditionally unitary states. Decentralization, then, is a concept that has broken the theoretical boundaries between unitary states and federal states, transcending them. Therefore, a comparative study not only between federal countries but also between unitary countries is required. The aim of this paper is to compare the process of decentralization in two countries with completely different institutional settings (Argentina and Denmark) in order to measure the degree of fiscal decentralization reached, to understand how this process has operated throughout the last decade and which outcomes has been achieved in these two countries.