The interest earned on a United States EE savings bond depends on when the latest bond was issued. For example, the latest bonds issued ( bonds from May 1, 2013 to October 31, 2013) earn a 0.20% annual interest rate that is compounded semiannually and earns interested for up to 30 years. On these bonds, the interest rate is a fixed rate, which means it will not change for the first 20 of those 30 years. After 20 years, the rate at which the EE bond earns interest is subject to change.
However, any EE Bonds that were bought from May 1997 through April 2005 earn a variable rate of interest that changes every six months.
And any EE Bonds bought before May 1997 earn different interest rates depending on when they were purchased.