Beyond retail savers, banks that are holding cash in excess of required reserves have no choice but to accept the negative interest rates that central banks impose; indeed, they could not hold, manage, and transfer those excess reserves if they were held as cash, rather than in a negative-yielding account with the central bank. Of course, this is true only so long as the nominal interest rate is not too negative; otherwise, switching to cash – despite the storage and safety costs – starts to make more sense.