The upper chamber of Russian parliament approved draft Law No. 297807-6 on July 10, 2013 which changes the Federal Law on Customs Tariff and introduces a differentiation in mineral tax rates. The law changes the previous flat rate of tax on natural gas producers to a system that consider the level of difficulty of extraction of the fuel as well as being linked to domestic gas price and the oil price. The rate of tax depends on the soil permeability, the depletion of the deposit and the size of the oil reservoir. The Law will become effective one month after its publication in the Official Gazette and aims to stimulate new investment projects for the development of enhanced oil recovery.