Working Paper No. 301
By Stephen Millard and Matthew Willison
The Bank of England's second core purpose is to maintain the stability of the financial system. Payment systems, by supporting transactions, are a key aspect of this. In this paper, we examine the importance of smoothly functioning payment systems to the economy by extending a recently developed theoretical model of banks. In the model the risk of theft implies a cost to using cash. This risk can be avoided by depositing cash in banks and transferring money through an interbank payment system. However, agents are then exposed to the risk that the payment system is unreliable. Agents will use a payment system (rather than cash) to make transactions if the system is sufficiently cheap to use and/or it is sufficiently reliable. We show that the introduction of a payment system that buyers and producers choose to use unambiguously increases social welfare if it expands the number of trades occurring in the economy. This is more likely the more reliable is the payment system. When the introduction of a payment system does not increase the number of trades, social welfare may increase or decrease depending on the trade-off between the risk of using cash and the risk that the payment system is unreliable. We again show that the more reliable is the payment system, the more likely welfare is increased by its introduction and we illustrate how this benefit might be quantified.