We study how corporate tax reforms affect aggregate capital fluctuations in a general equilibrium dynamic investment model with firm heterogeneity, capital adjustment costs, and irreversibility wedges. We show that corporate tax changes influence capital misallocation and the propagation of aggregate shocks across tax regimes. Using microdata, we quantify these effects through after-tax investment frictions. Our findings offer new insights into tax policy's role in shaping capital dynamics and macroeconomic fluctuations.