Uztáriz’s Theórica was the most influential Spanish economics text throughout the country and its colonies as a whole in the eighteenth century. It soon became the object of well-honed critical analyses. Although this controversial reception touched on many of the arguments put forward in the work, taxation was undoubtedly a major focus of the interpretations. This chapter aims to define the outlines of the long shadow cast by the Theórica over the three decades after its publication. It is divided basically into three sections. The first analyses Uztáriz’s core proposal for taxation, the second deals with tariffs and the customs system. and the third examines the controversial reception of both, particularly the former, among political economists and reformers of the day. The chapter underlines that Uztáriz conceived taxation (taxes and tariffs) as a linchpin for establishing a “new policy” that would bring Spain into line with Europe’s leading countries and promote the recovery of comercio útil, especially domestic manufacturing.