The adoption of tax systems in different industries has been a discussion subject in academic circles for several years. Although a conclusion hasn’t been reached yet about which system is more efficient, there is a consensus that tax systems should be neutral. In other words, the level of investment and the economic activity shouldn’t be affected by its application. The issue becomes even more complex when the industry being analyzed is upstream, to the extent that it is a commodity essential to ensure national security and autonomy, which usually has restricted access. In Brazil, for several years the oil industry wasn’t even able to guarantee domestic oil self sufficiency, but recently, with the discovery of huge Tupi field in the subsalt region, a new era began in the country s oil industry. Besides the enormous potential to increase production of domestic oil, there are several issues regarding the regulatory framework that should be adopted, since the government’s goal for the regulatory framework should be to attract investment and capture the maximum economic return of its reserves. Under current circumstances, it’s very likely that the government will consider increasing its share of the production from the subsalt region. However, the real benefits of adopting a more restrictive policy should be carefully analyzed, as heavy investments will be needed to develop the reserves in this region. This paper analyzes five tax systems currently adopted in different countries, besides the current regulatory framework in Brazil, aiming to evaluate how the country can retain the maximum economic benefit possible, through the analysis of different tax rates, its impact on investment attractiveness and the disincentive of private investment in acquiring concession of great reserves.