“Negative interest rate” is a phrase seemingly designed to confuse all but the experts. Instead of paying interest on commercial banks’ “excess” reserves held by the central bank, the central bank taxes these deposits. The idea is to impel the banks to reduce their unspent balances and increase their lending or investments. In the case of the European Central Bank, there is a technical reason: to increase the supply of high-class bonds for President Mario Draghi’s ongoing program of quantitative easing.

…

But, as the World Bank has pointed out, negative rates can have undesirable effects. They can erode bank profitability by narrowing interest-rate margins. They can also encourage banks to take excessive risks, leading to asset bubbles. Lower interest rates on deposits may cause large sections of the economy to become cash-based, while pension and insurance companies may struggle to meet long-term liabilities at a fixed nominal rate.

But, quite apart from these problems, the real case against negative interest rates is the folly of relying on monetary policy alone to rescue economies from depressed conditions. Keynes put it in a nutshell: “If we are tempted to assert that money is the drink which stimulates the system into activity, we must remind ourselves that there may be several slips between the cup and the drink.” His list of “slips” is well worth recalling:

“For whilst an increase in the quantity of money may be expected…to reduce the rate of interest, this will not happen if the liquidity-preferences of the public are increasing more than the quantity of money; and whilst a decline in the rate of interest may be expected…to increase the volume of investment, this will not happen if [profit expectations] are falling faster than the rate of interest; and whilst an increase in the volume of investment may be expected…to increase employment, this may not happen if the propensity to consume is falling off.” …

The truth, however, is that the only way to ensure that “new money” is put into circulation is to have the government spend it. The government would borrow the money directly from the central bank and use it to build houses, renew transport systems, invest in energy-saving technologies, and so forth.

The False Promise Of Negative Interest Rates
https://www.socialeurope.eu/2016/05/false-promise-negative-interest-rates/