The goal of this research is to outline e the vectors for reducing the scale of “shadow” economy, improving control over legalization of the income of small and medium businesses in the constituent entities of the Russian Federation, and determining tax potential of the regions in separate sectors economic sectors in the current context. The subject of this research is the role and place of legalization of shadow business as the factor of stimulating the economic activity of the regions. The article examines various approaches of the experts towards the concept of “shadow” economy in the modern conditions. Analysis is carried out on the peculiarities of development of “shadow” economy in certain economic sectors (such as construction, wholesale and retail, alcohol production, etc.) in Russian regions (using the example of the Republic of Dagestan). Comparative study is conducted on various indicators in the constituent entities of North Caucasus Federal District and the Russian Federation. Special attention is given to the measures aimed at reduction of the scale of “shadow” economy and improving control over legalization of the income of entrepreneurial activity with regards to increasing tax revenues from small and medium businesses and determining tax potential of the regions. Recommendations are made for reducing the scale of the “shadow” economic sectors, increasing tax revenue from small and medium businesses, determining tax potential of the region in separate economic sectors, stimulating economic activity of small business within the limits of economic security. Based on the acquired results, the author makes suggestions on legalization of the “shadow sector” in separate branches of the economy, as well as improvement of the effectiveness of measures of interdepartmental cooperation of tax, law enforcement and registering bodies aimed at determination of tax potential of the regions in the current context.