When Does Coordination Pay?

In a continuous time model of two symmetric open economies, with a floating exchange rate, we find that the pay-off to the policy coordination depends systematically on the heterogeneity of their inflation experience. While monetary policy coordination improves welfare when there is a common rate of underlying inflation, it exacerbates the `time-consistency' problem arising when there are differences. Since the principle of `certainty equivalence' applies to time-consistent policy in linear quadratic models, we are also able to give a stochastic interpretation of the deterministic results.