The supply of bribes: Evidence from roadway tolls in the D.R. Congo

Why is corruption so resilient? While many recent papers examine interventions seeking to discipline bureaucrats, less is known about the elasticity of citizens’ supply of bribes. This randomized controlled trial explores citizen bribe payment at roadway tolls in Kananga, D.R. Congo. We offer financial and social incentives to motorcycle taxi drivers to bring receipts proving that they paid the legal toll. Observing a 7 to 10 percentage point increase in legal transactions due to financial incentives, we estimate an elasticity of citizen supply of bribes ranging from -0.45 to -0.95. Social incentives have no effect. We argue that limited responsiveness to large financial incentives reflects the fact that bribe payment reduces driver time at tolls by nearly 70%. Toll officers know their payer population is highly time constrained and so endogenously create an elaborate payment procedure to increase the time costs of paying the tax instead of a bribe. This result suggests that citizen-side anticorruption interventions may have limited effectiveness in settings in which (i) citizens are time constrained and bribes expedite the transaction, or (ii) bureaucrats can endogenously increase the hassle costs of citizen compliance.