Zero interest-rate policy (ZIRP) is a "macroeconomic concept describing conditions with a very low "nominal interest rate, such as those in contemporary "Japan and December 2008 through December 2015 in the "United States. ZIRP is considered to be an "unconventional monetary policy instrument and can be associated with slow "economic growth, "deflation, and "deleverage.
Under ZIRP, the "central bank maintains a 0% "nominal interest rate. The ZIRP is an important milestone in "monetary policy because the central bank is no longer able to reduce nominal interest rates—it is at the zero lower bound. Conventional monetary policy is at its maximum potential to drive growth under ZIRP. ZIRP is very closely related to the problem of a "liquidity trap, where nominal interest rates cannot adjust downward at a time when savings exceed investment.
Others argue that when monetary policy is already used to maximum effect, to create further jobs, governments must use "fiscal policy. The "fiscal multiplier of government spending is expected to be larger when nominal interest rates are zero than they would be when nominal interest rates are above zero. "Keynesian economics holds that the multiplier is above one, meaning government spending effectively boosts output. In his paper on this topic, "Michael Woodford finds that, in a ZIRP situation, the optimal policy for government is to spend enough in stimulus to cover the entire "output gap.
Chris Modica and Warren Sulmasy find that the ZIRP policy follows from the need to refinance a high level of "US public debt and from the need to recapitalize the world's banking system in the wake of the "Financial crisis of 2007–2008.
The "zero lower bound problem refers to a situation in which the short-term nominal interest rate is zero, or just above zero, causing a "liquidity trap and limiting the capacity that the central bank has to stimulate economic growth. This problem returned to prominence with the "Japan's experience during the 90's, and more recently with the "subprime crisis. The belief that monetary policy under the ZLB was effective in promoting economy growth has been critiqued by economists "Paul Krugman, "Gauti Eggertsson, and "Michael Woodford among others. "Milton Friedman, on the other hand, argued that a zero nominal interest rate presents no problem for monetary policy. According to Friedman, a central bank can increase the "monetary base even if the interest rate vanishes; it only needs to continue buying bonds. (Note: The quote from footnote #3 may be misleading. Friedman was talking about Japan in 1989, when Japan's very tight monetary policy produced deflation which resulted in a zero interest rate. Friedman wasn't exactly advocating the ""quantitative easing" that's been the Fed's strategy from 2008 to 2014. (7/30/2014))