We develop a theory of money and credit as competing payment instruments, then put it to work in applications. Buyers can use cash or credit, with the former (latter) subject to the inflation tax (transaction costs). Frictions that make the choice of payment method interesting also imply...

We construct a monetary economy in which agents face aggregate demand shocks and heterogeneous idiosyncratic preference shocks. We show that, even when the Friedman rule is the best interest rate policy the central bank can implement, not all agents are satiated at the zero lower bound and...