In a world increasingly driven by digital innovation, the role of physical currency is facing unprecedented challenges. A recent working paper published by the International Monetary Fund’s Monetary and Capital Markets Department delves into this critical issue. Authored by IMF economists Marco Pani and Rodolfo Maino, and informed by research support from global institutions including the IMF, the Society of Government Economists, and the International Atlantic Economic Conference, the study poses a provocative question: could the growing adoption of digital currencies inadvertently drive cash into extinction?
Cash as a Fallback: A Role Under Threat
While cash usage is declining across much of the world, particularly in technologically advanced societies, its importance as a backup payment method is often overlooked. Cash offers unparalleled benefits chief among them anonymity, independence from third-party systems, and the ability to function even during technological disruptions or disasters. These features, while valuable to society, are often underappreciated by individual users who focus more on convenience or rewards offered by digital payment options. Because of this discrepancy, cash may gradually vanish not because it’s obsolete, but because market participants stop demanding or accepting it leading to its quiet but irreversible exit.
The researchers argue that the disappearance of cash is not likely to come from policy decisions, but rather from cascading market behavior. If customers stop carrying cash, merchants stop accepting it; and if merchants stop accepting it, customers will have no reason to carry it. This mutual reinforcement creates a feedback loop that can easily tip the system toward a single-currency dominance even if multiple payment options would be socially optimal.
The Merchant-Customer Model: Mapping Payment Behavior
At the center of the study lies a dynamic two-sided market model that simulates the decision-making behavior of merchants and customers. Each party must choose which payment instruments to use or accept based on fixed costs, variable costs or benefits, and the expected behavior of the other side. Using this framework, Pani and Maino examine both two-currency and three-currency systems. In the simpler two-currency version, the market is split between cash and cards. Simulations show that while multiple equilibria are possible including those where both payment methods coexist certain combinations of parameters and initial conditions can lead to the dominance of one instrument.
Even small shifts in usage, the study finds, can trigger a domino effect. For instance, if just a few merchants stop accepting cash, some customers may abandon it altogether. As customer usage declines, even more merchants drop cash, until it disappears from the market entirely. Importantly, once this state is reached, the system does not naturally revert. The reintroduction of cash would require massive and coordinated effort—a feat unlikely to occur organically.
Adding a Digital Currency: More Options, More Instability
When a third currency a digital one is introduced into the model, the complexity increases substantially. Now, merchants and customers can choose from seven combinations of usage and acceptance, from carrying or accepting only one instrument to all three. The simulations explore how a digital currency affects the market when introduced on different scales small (1% adoption), medium (5%), and large (25%) and in different ways: as a complement to cash or as a substitute.
The results are mixed and, in some cases, alarming. In several scenarios, the digital currency succeeds and coexists with the legacy systems. In others, it replaces either cash or cards entirely. In a few cases, it replaces both. But perhaps the most striking outcome is one in which the digital currency fails to gain traction but still manages to disrupt the existing equilibrium causing cash, or even both legacy currencies, to vanish. This demonstrates the fragility of the payment ecosystem and the potentially disproportionate impact of even modest innovations.
When Success Means Disruption: Lessons for Policymakers
The success of a new currency, according to the study, depends heavily on the scale and method of its launch. Large-scale introductions—especially when the digital currency is framed as a substitute for cash are more likely to cause market disruptions. Conversely, small-scale or complementary launches are less impactful but also less likely to succeed in shifting user behavior. However, even these “soft” launches can, under the right conditions, disturb the balance and push the system toward unintended consequences, including the total disappearance of cash.
This research carries vital implications for central banks and financial regulators. As governments and private firms explore the rollout of CBDCs and other digital payment systems, they must be acutely aware of how these tools interact with existing infrastructure. If cash is to remain as a public good a reliable, inclusive, and privacy-preserving fallback then deliberate measures may be required to protect its role in the system.
Anticipating the Future of Money
As the global payment landscape evolves, decisions made today could have long-term implications for how money is used, who can access it, and what choices people have in managing their finances. This IMF study offers a sobering reminder that innovation, while beneficial, is not without risk. It calls on policymakers to look beyond the surface appeal of digital efficiency and consider the deeper market dynamics that might push cash quietly but permanently into obsolescence. In doing so, it lays the groundwork for more informed, cautious, and inclusive strategies for the future of money.