Many jurisdictions levy sizable fines and fees (legal financial obligations, or LFOs) on criminal defendants. Proponents argue LFOs are a “tax on crime” that funds courts and provides deterrence; opponents argue they do neither. We examine the fiscal implications of lowering LFOs. Incentives to default generate a “Laffer” curve with revenue eventually decreasing in LFOs. Using detailed administrative data, however, we find few defendants demonstrably on the right-hand side of the curve. Those who are tend to be poor, Black, and charged with felonies. As a result, decreasing LFOs for the average defendant would come at substantial cost to governments.