You cannot purchase paper EE bonds, but you can purchase paper I bonds. Interest paid on a Series EE Savings Bond depends on when it was purchased. If an EE Savings Bond was purchased after May 2005, it earns a fixed-rate of return. Any Series EE Savings Bond issued from May 1997 through April 2005 earns variable rates of interest, based upon 90% of the six-month average rate of five-year treasury security yields. Series I Savings Bonds earn a combined interest rate, a fixed-rate disclosed when you buy, and a semi-annual inflation adjustment.