The financial crisis has been affected many global stock markets, as well as the Viet Nam stock exchange. This study analyzes the impacts of tax policy on market risk for the listed firms in the non-banking financial service and investment industry, so-called financial service industry, as it becomes necessary. First, by using quantitative and analytical methods to estimate asset and equity beta of total 10 listed companies in Viet Nam financial service industry with a proper traditional model, we found out that the beta values, in general, for many companies are acceptable. Second, under 3 different scenarios of changing tax rates (20%, 25% and 28%), we recognized that there is not large disperse in equity beta values, estimated at 1,048, 1,050 and 1,052.These values are just little higher than those of the listed VN construction firms but much higher than those of listed banking firms. Third, by changing tax rates in 3 scenarios (25%, 20% and 28%), we recognized equity /asset beta are most the same (0,23 and 0,16) if tax rate increases from 20% to 25%, then goes up from 25% to 28%.