Pass-through determines how consumers respond to Pigouvian taxes or unconventional fiscal policy. We investigate the impact of imperfect price information on pass-through of commodity taxes. Our theoretical model predicts that the pass-through rate increases with the share of well-informed consumers. Pass-through is higher for the minimum price, paid by well-informed consumers, than for the average price, paid by uninformed consumers. Moreover, pass-through to the average price is non-monotonic with respect to the number of sellers. An empirical analysis of multiple recent tax changes in the German and French retail fuel markets supports these predictions.