Studying the fairness of taxation is not separable from the general emergence of the social fairness, but some features of its own could be determined. In this paper I examined the problem of the fairness of taxation and drew up the details of the optimal tax system. One single chapter was devoted to the analysis of the relation between the notion of fairness and equity and another was devoted to the analysis of the question of sameness, which is necessary for the understanding of the fairness of taxation.