In this paper, we estimate the elasticity of profits before taxes with respect to the net-off marginal effective tax rate in a context of frequent tax reforms.This measurement is relevant, given the wide margin of maneuver that firms have to respond to changes in taxes, and the importance of corporate income taxes on economic activity and the fiscal balance.The analysis is carried out for the tax reforms implemented in Colombia, during the period 2008-2014, using Least Squares in two stages and Endogenous Quantile Regression for Panel Data.The marginal effective tax rates used in the estimations shows that the corporate tax burden of firms is lower than the statutory tax rate defined by law, due to tax deductions and tax exemptions established by Law.In turn, the results of the elasticities show that the firms' responses depend on the specific tax reform and on the companies' characteristics.