Using individual credit bureau data matched with cash windfalls from fracking, we estimate that windfall recipients reduce debt-to-income by 2.4 percentage points relative to no-windfall controls. Debt repayment effects are 3 times stronger for subprime individuals than for prime individuals. Based on the timing of upfront versus continuing cash payments, debt repayment coincides with the timing of payments but not with news about future payments. These findings present a challenge for purely forward-looking models of debt. Indeed, when we incorporate a windfall shock into a forward-looking model, the model predicts an increase in debt that runs counter to our evidence of debt repayment.