Liquidity traps, debt relief, and macroprudential policy: a mechanism design approach∗

I present a unified framework to analyze debt relief and macroprudential policies in a liquidity trap when households have private information. I develop a model with a deleveragingdriven recession and a liquidity trap in which households differ in their impatience, which is unobservable. Ex post debt relief stimulates the economy, but anticipated debt relief encourages overborrowing ex ante, making savers worse off. Macroprudential taxes and debt limits prevent the recession, but can harm impatient households, since the planner cannot directly identify and compensate them. I solve for optimal policy, subject to the incentive constraints imposed by private information. Optimal allocations can be implemented either by providing debt relief to moderate borrowers up to a maximum level, combined with a marginal tax on debt above the cap, or with ex ante macroprudential policy a targeted loan support program, combined with a tax on excessive borrowing. These policies are ex ante Pareto improving in a liquidity trap; in normal times, however, they are purely redistributive. These results extend to economies with aggregate uncertainty, alternative sources of heterogeneity, and endogenous labor supply. JEL classification: D82, E21, E32, E44, E62