The article devoted to evaluation the influence of preferential tax treatment for charitable expenses of commercial organizations. The aim of the study is to prove that the introduction of tax incentives for charitable activities of commercial organizations will promote their charitable expenses. Banking sector’s organizations were selected for the empirical basis of the study; because the information about the charitable expenditure of other organizations is not available .The study has used a sample of 49 banks operating in Irkutsk Oblast as a constituent member of the Russian Federation in 2011-2014. The study sample was divided into three groups according to the principle proposed for the evaluation of social responsibility of banks in the United States. The current level of participation of banks in corporate philanthropy is evaluated in view of preferential taxation as a mechanism to reduce the cost of charitable services for the company. The study attempts to construct a theoretical model describing the effect of tax incentives for the financing of the charitable sector, as well as to find the optimal limit registration of charitable expenditure as an expense. It has also been found that, regardless of the charitable expenditures limit set as part of total expenses, the majority of credit organizations could exploit a maximum potential growth of donations (from 49,5 % to 74 % of the studied credit institutions, depending on the chosen accounting limit). It is concluded that introduction of preferential tax treatment might mean a possible rise in charitable expenditures, and the optimal level of charitable expenditure accounts as an expense in terms of budget efficiency is substantiated.