The purpose of the present paper is to investigate the revenue impact generating from substitution of Value Added Tax for current corporations tax of economic units in The Mazandaran Province. According to the province Bureau of Tax, in 2004, there were 19576 corporations file tax of which only 7856 were subjected to tax. Present study used a random sample of 365 corporations from different cities in the province of which the necessary data for 357 of them could be collected. Also due to the vast differences between the performances of corporations and economic units in the province, the statistical analysis were performed in five different scenarios. Our findings based on regression models and also the mean difference test for current tax ...