Series EE Bond

What Does Series EE Bond Mean?
A non-marketable, interest-bearing U.S. government savings bond that is guaranteed to at least double in value over the initial term of the bond, typically 20 years. Most Series EE bonds have a total interest-paying life that extends beyond the original maturity date, up to 30 years from issuance.  

Investopedia explains Series EE Bond
Series EE bonds issued after May 2005 are assigned a fixed coupon rate; rates are set twice per year in May and in November and apply to all issuances for the ensuing six months. Bonds issued after this date increase in value monthly, but interest payments are semiannual.

Paper EE bonds are issued at a 50% discount to par, while bonds purchased electronically (through TreasuryDirect) are purchased at face value; the latter are still guaranteed to be worth twice their original value at first maturity date after 20 years, and pay interest the same way as paper EE bonds.    

Series EE bonds are considered ultra-safe, low-risk investments. Interest on Series EE bonds is typically exempt from state and local taxes, and coupon rates are assigned based on a percentage of the long-term Treasury rates at the time of issuance.  

Savings bonds must be held at least one year before they can be redeemed.  If they are held for less than five years, a penalty of three months' interest will be assessed when the bonds are redeemed.