In many African countries, large discrepancies exist between revenues implied by published tariff rates multiplied by estimated import volumes and actual receipts. We develop a stylised trade model where average and marginal tariff rates diverge and incorporate insights from this model into a computable general equilibrium model of an African economy (Mozambique) to study the implications of trade policy reform. Model simulations indicate that lowering tariff rates and reducing duty-free importation in a manner that maintains official revenue benefit nearly everyone. The main exception is those who benefited from duty-free imports in the base