Using a quantitative example, this article analyses the impact of different fiscal regimes (current tax system, tax on the financial result and additional income tax) on the economics of the oil production in Russia. It conducts a sensitivity analysis in different tax regime scenarios showing how sensitive the net present value (NPV) of the analyzed project and the discounted government revenues are to any oil price change. It concludes that given high oil price uncertainty and remaining resources deterioration the existing fiscal system ought to be replaced by a more flexible tax regime which takes into account oil producers expenses.