Some rates are based on inflation. I Bonds is the sum of two rates. It is unchanging for the life of the bond. Fixed rates are announced each May 1 and November 1 for bonds issued in the following six months. A three-month interest penalty is charged if the bonds are redeemed within the first five years.
Interest is credited monthly and compounded semiannually.
A three-month interest penalty is charged if the bonds are redeemed within the first five years. Unlike other series EE Bonds, interest is credited monthly and compounded semiannually. These bonds were issued with two market-based rates, short term and long term. Both are related to the yields on Treasury securities. A new rate is announced May 1 and November 1 each year and calculated to reflect the T-bill yields of the prior three months.