How is the interest on EE bonds calculated ?

As of January 1, 2012, paper savings bonds will no longer be sold at financial institutions. This action supports Treasury’s goal to increase the number of electronic transactions with citizens and businesses.EE Bonds are reliable, low-risk government-backed savings products that you can use toward financing education, supplemental retirement income, birthday and graduation gifts, and other special events. Series EE Bonds purchased on or after May 1, 2005, earn a fixed rate of return, letting you know what the bonds are worth at all times. EE Bonds purchased between May 1997 and April 30, 2005, are based on 5-year Treasury security yields and earn a variable market-based rate of return.