I recently learned that I Bonds can pay 0% interest.  Although their interest calculation includes both a fixed rate and an inflation rate which is calculated every 6 months, the fixed rate is not exactly a fixed rate.  In other words, it is not guaranteed.  It seems to me the Treasury shouldn't use the term fixed rate in this case because it leads one to believe that a bond would at least pay the fixed rate in the absence of any inflation factor.  The Treasury explains that since we have experienced a negative inflation rate the bonds will pay 0% interest for a period of time until the inflation rate turns positive again.  I wonder how many other investors realized this?  It came as a big surprise to me when I used the Treasury Bond Calculator to determine the current value of my bonds.