The number of operations of companies s reorganization accomplished in Brazil and the involved values constantly grow, but it is still very small if compared with the USA. To relieve the heavy Brazilian tax burden, as well as to maintain the competitiveness of the American companies, the managers of the great companies of those two countries constantly invest in the development of structures that join value for the shareholders, what is observed also in operations of companies s reorganization. This research has the objective to analyze the tax planning in operations of companies s reorganization in Brazilian and American companies that joins value for the shareholders, being used the methodology of study of case of two operations accomplished in Brazil and one in the USA. The data of the research were collected through documental research and perception questionnaires, elaborated being used the Escala Likert. The interpretation and analysis of the data based on the theoretical references, based in revision of pertinent literature to the study area. The results of the research evidenced the aggregation of value so much for the shareholders in the operations accomplished in the USA as in Brazil, but due to the harmonization of the Brazilian accounting with the international, insecurity appears as for the effectiveness of the current structures of tax planning used. As recommendation resulting from the research, suggests the accomplishment of works for the development of models that you/they measure the juridical insecurity and the possible changes of the fiscal legislation in the value of the proportionate tax economy to the shareholders.