Payments systems are typically characterized by some degree of tiering, with upstream firms (clearing agents) providing settlement accounts to downstream institutions that wish to clear and settle payments indirectly in these systems (indirect clearers). Clearing agents provide their indirect clearers with an essential input (clearing and settlement services), while also competing directly with them in the retail market for payment services. The authors construct a model of a clearing agent with an indirect clearer to examine the clearing agent's incentives to lever off its upstream position to gain a competitive advantage in the retail payment services market. The model demonstrates that a clearing agent can attain this competitive advantage by raising the indirect clearer's costs, but that the incentive to raise these costs is mitigated by credit risk to the clearing agent from the provision of uncollateralized overdrafts to its indirect clearer. The results suggest that tiered payments systems, which require clearing agents to provide overdraft facilities to their indirect clearers, may result in a more competitive retail payment services market.