Must-Read: Matthew Rognlie: What Lower Bound? Monetary Policy with Negative Interest Rates

Must-Read: Matthew Rognlie: What Lower Bound? Monetary Policy with Negative Interest Rates: “Recently, several central banks have set interest rates as low as -0.75%… suggesting that, in practice…

…money demand remains finite even at negative nominal rates. I study optimal monetary policy in this new environment, exploring the central trade-off: negative rates help stabilize aggregate demand, but at the cost of an inefficient subsidy to paper currency. Near 0%, the first side of this tradeoff dominates, and negative rates are generically optimal whenever output averages below its efficient level. In a benchmark scenario, breaking the ZLB with negative rates is sufficient to undo most welfare losses relative to the first best. More generally, the gains from negative rates depend inversely on the level and elasticity of currency demand. Credible commitment by the central bank is essential to implementing optimal policy, which backloads the most negative rates. My results imply that the option to set negative nominal rates lowers the optimal long-run inflation target, and that abolishing paper currency is only optimal when currency demand is highly elastic.