In this paper we present an ontological framework for modeling the core concepts of personal income taxes, based on the Italian law. The ontological analysis focuses on an highlevel conceptualization of the main principles of tax legislation, and is largely based on contributions from legal doctrine and the most relevant Italian Constitutional Court's decisions in tax law. As such, the model may serve as a framework to be specialized by further ontological modules. In addition to the core ontological concepts of tax domain, an emphasis is given to the norms application process, which we believe helps to explain the complicated way taxes are imposed. In our approach, the final result of this process is a tax position, which accounts for the relationship between the taxpayer and the treasury with respect to a particular tribute. Copyright 2013 ACM.
