While recent comments by Federal Reserve Chairman Jerome Powell indicate that the Fed hopes to avoid resorting to negative interest rates during the next recession, without them the central bank’s ability to stimulate growth may be limited. Should negative interest rates one day become a reality in the U.S., the tax code will need to be amended. Otherwise, not only will consumers be forced to pay to “invest” their savings, but savers will face higher taxes.

According to Bloomberg.com, 30% of all bonds, some $17 trillion world-wide,...