ABSTRACT
This chapter aims to carry out a sequential/serial study of the data obtained and the amounts collected and spent, searching for an evolution line of fiscal traits. The sisas were first placed on Portuguese Jews in 1316, as an increase of the services granted to the monarch. Concessions, in fact, were not municipal taxes, but payments granted to the central power, in a kind of “partnership” where there was clearly the favored party and the party prejudiced, similar to the Castilian servicios. The central issue to note is that since the beginning of the fifteenth century, the sisas are already the flagship of Portuguese tax collection. In Setubal’s case, one of the most important Portuguese ports regarding international trade, located in the Sado estuary 45 kilometers south of Lisbon, it is necessary to make some observations: first, the relevance of local economic production, namely salt, wine, fishing and shipbuilding.
