In an economy with substantial informality, a carbon tax can produce fiscal co-benefits that improve economic performance in addition to reducing carbon dioxide emissions. If the carbon tax revenues are used to cut production or labor taxes on formal firms, particularly those not in the energy sector, the cost of imposing the carbon tax is reduced, and there may even be net economic benefits. These tax cuts can also provide an incentive for informal firms to move to formal parts of the economy. This study confirms these hypotheses using a computable general equilibrium model for Côte d’Ivoire. However, the scale and even the sign of overall economic impacts and formal-informal sectoral interactions are sensitive to the scheme and scale of revenue recycling. The largest fiscal co-benefits, in terms of gross domestic product and economic welfare gains, would occur when the entire carbon tax revenue, after keeping the government revenue neutral, is used to cut existing labor or production taxes for non-energy formal firms. Reducing the existing value-added tax also increases gross domestic product and economic welfare, but without reducing the informality. The study also shows that energy producers should be exempted from using the carbon tax revenues to cut their production or labor taxes; otherwise, carbon dioxide reduction decreases due to a rebound effect. Although a carbon tax with lump-sum transfers of revenues is progressive, it would be economically inefficient because of gross domestic product and welfare reduction and lack of incentives to encourage informal activities to move to the formal parts of the economy.