Despite all the importance of strategic planning in organizations of the private industry, similar experiences described in the public administration context are rare. Furthermore, the methodologies used in these cases are neither clear nor consolidated as they should be, because they are, in general, adaptations from their parallels of the private sector. This article aims at identifying the main elements concerning the Situational Strategic Planning (PES) methodology, and its adoption by the Tributary Administration Coordination (CAT) of the State of São Paulo. It consists of an exploratory study, introducing a notorious experience within the Brazilian tributary administration, which qualifies for a unique case study method. The text investigates: the main aspects of strategic management in the public administration; the process of strategic planning inside CAT with the PES adoption; the main results achieved; and, finally, the conclusions considering the case context.