what is a series ee bond 
the series ee bond often referred to as a patriot bond is a non marketable interest bearing u s government savings bond these bonds are guaranteed to at least double in value over the typical 20 year initial term some series ee bonds have total interest paying lives that extend beyond the original maturity date up to 30 years from issuance coupon rates for series ee bonds are determined at the time of issuance and are based on the percentage of the long term treasury rates 