Multiple equilibria arise in standard New Keynesian models when the nominal interest rate is set according to the Taylor rule and constrained by a zero lower bound (ZLB). One of these equilibria is deflationary and referred to as an expectations-driven liquidity trap (ELT) as it arises because of the de-anchoring of inflation expectations. This study demonstrates that a simple tax rule responding to inflation can prevent a liquidity trap from arising without increasing government spending or debt. We analytically investigate the necessary and sufficient conditions to prevent an ELT and show that both the frequency and persistence of ELT episodes affect the extent to which the tax rule must respond to inflation. In brief, the higher the frequency or the longer the persistence of the ELT, the greater the response of the tax rate must be.

当名义利率根据泰勒规则设定并受零下限 (ZLB) 约束时，标准新凯恩斯模型中会出现多重均衡。其中一个均衡是通货紧缩的，被称为预期驱动的流动性陷阱（ELT），因为它是由于通胀预期的脱锚而出现的。这项研究表明，应对通货膨胀的简单税收规则可以在不增加政府支出或债务的情况下防止出现流动性陷阱。我们分析调查了防止 ELT 的必要和充分条件，并表明 ELT 事件的频率和持续性都会影响税收规则必须对通货膨胀做出反应的程度。简而言之，ELT的频率越高或持续时间越长，税率的反应就必须越大。