The subject of this article is the types of relationship between economic development and degree of income inequality in the regions of the Russian Federation. Research methods: testing the modified Kuznets hypothesis; relative deflating of regional parameters; calculating the differentiation and localization coefficients; constructing the Lorentz curves; correlation and regression analysis. Obtained results: 1) for Russian regions author discovered significant direct statistical relationship between the Gini and funds coefficients and the level of real per capita income with increasing returns, as well as less strong direct relationship between coefficients of differentiation mentioned above and the real GDP per capita with diminishing returns; 2) the “social wellbeing” coefficient is proposed and calculated for the regions, which based on localization index of real per capita income relative to the differentiation coefficient, and 3) the degree of interregional disparities in the Russian Federation is evaluated on the basis of the Gini coefficient, coefficient of variation and relative entropy for the nominal and real income and GRP per capita, and Lorenz curves for them are constructed. In this paper, author concluded: 1) presently the level of economic development of the Russian Federation regions negatively affects their income equality due to most of them are on the ascending branch of the S. Kuznets curve, 2) “social welfare” coefficient changes the positions of the middle-income regions more, than that of other regions, and 3) two factors have a positive impact on reducing the regional disparities: more ratio of total personal income to GRP in poor regions relative to rich ones (i.e. greater “social orientation” of poor regions), and positive correlation between income and the cost of living in the regions. The obtained results can be used by researchers in further testing the modified Kuznets hypothesis, as well as by local authorities in the income policy optimization at the regional level.

The subject of the article is the risk, returnm and efficiency of the tax systems in the regions of the Russian Federation. Research methods: deflating GRP and tax revenues at regional level; calculating the standard deviations; G. Markowitz portfolio approach; W. Sharpe ratio calculating; correlation and regression analysis. Results obtained: 1) comparative risk profile of various taxes and their groups in the Russian Federation; 2) clustering the Russian regions in terms of risk and return of tax systems; 3) regression between the risk of regional tax systems, relative scale of regional economics and tax return based on panel data of the Russian regions in 2006-2012; 4) ranking of the RF regions on the effectiveness of their tax systems, estimated by W. Sharpe ratio. In the paper, the authors have concluded: 1) all taxes (tax group) collected in the Russian regions demonstrate a positive statistical relationship between return and risk, but with different correlation; 2) the risk of regional tax system depends on the structure of tax revenues in given region, the risks of collected taxes and the covariance of different taxes revenues to each other, and joint effect of these factors is estimated by means of portfolio approach by G. Markowitz; 3) the correlation between return and risk of the tax systems of the subjects of Russian Federation considering the scale of regional economics accounts for 75 %; 4) the risk of the Russian tax system is significantly provided by 19 major high-risk regions with more than 65 share in the total state tax revenues; 5) the effectiveness of regional tax systems estimated by the Sharpe ratio depends on both the objective and subjective factors affecting the yield and volatility of tax revenues in a region. Obtained results can be used by researchers in further dynamic and comparative analysis of regional tax systems’ risk and return, as well as in identifying the reserves for increasing the regional tax policy effectiveness.