The purpose of this article is the presentation of the main issues related to the optimal level of legislation governing the international financial flows. Well-designed regulations enhance the creation of stable and secure investment climate. On the one hand the rules support the freedom of investment and strengthen the competitive position of the territory. On the other they allow the effective fight against financial frauds, tax evasion and the erosion of the tax base. The paper analyses the risks associated with the lack of regulation of capital flows, as well as the consequences of too strict controls and excessive tax rules. It also presents international initiatives of developed countries, aimed both at securing the national tax systems against the loss of tax revenue due to harmful tax practices, and at improving financial market transparency and the security of international markets.