This dissertation analyzes the relationships between the political influence of business elites, tax regimes and inequalities in three countries: El Salvador, Costa Rica and Panama. To this end, an exhaustive review of fiscal information, tax reforms and social inequality is carried out, and business influence in the design, formulation and application of fiscal policies is reconstructed from critical junctures of fiscal reform. It focuses on the two decades between 2000 and 2019, without ignoring previous historical trajectories, structural conditions and the ongoing transnational tax agenda.The research has been framed within the field of fiscal sociology to investigate and explain the relationships between taxes, the state and business elites. Chapter 2 describes the theoretical categories that have guided this research based on fiscal sociology, the theory of power and political influence and the sociology of elites, in dialogue with Bob Jessop's strategic relational approach and other critical approaches to political economy. In addition, the epistemic and methodological foundations that have guided the work are detailed, under a complexity and comparative approach with historical and relational foundations, with a use of historical analysis tools such as process tracing and the critical study of historical junctures. The work has been nourished by a wide variety of statistical, documentary, archival and testimonial sources, with 51 anonymized interviews with business representatives, politicians and experts from each of the countries interviewed.The empirical section of the dissertation is divided into four chapters, chapters 3, 4, 5, and 6, which provide a detailed account of tax structures, socioeconomic inequality and tax reform processes. First, Chapter 3 describes the general features of tax structures, the tax reforms passed in parliaments and their relationship with the production of inequalities. The three cases show important variations, but also convergences in terms of tax privileges for their corporate sectors. Likewise, the three countries have regressive tax structures with an emphasis on consumption taxes, the effects of which are insufficiently compensated by social spending.Following this analysis, the fiscal conjunctures are studied using process tracing, in chapters 4 to 6. In the Costa Rican case, the fiscal reforms of Abel Pacheco (2002-2006), Laura Chinchilla (2011-2012) and Carlos Alvarado (2018) were considered. For Panama, the reforms of Mireya Moscoso (2002-2003), Martín Torrijos (2004-2006) and the first two fiscal reforms of Ricardo Martinelli (2009-2011) were researched. In the case of El Salvador, it was addressed the situation of Antonio Saca (2004-2005), and the two reforms of Mauricio Funes in 2009 and 2011. Chapter 7 is a comparative effort that looks for convergences and divergences among the selected cases. It focuses on changes in tax regimes, tax privileges for elites, the impact on socioeconomic inequality, as well as variations and similarities in the patterns of business influence that explain these results of Central American fiscal policy. Finally, Chapter 8 synthesizes the main research findings and the future agenda for a Central American fiscal sociology. Through interactions with state elites and the use of instrumental resources and corporate structural capacities, fiscal regimes have been articulated with accumulation strategies and accumulation axes, and progressive alternatives and agendas have been blocked with less or more success. Moreover, elites employ strategies of fiscal immunity and impunity as ways of escaping the fiscal social relation. These dynamics are central to the production of fiscal and social inequalities.