Commodity Credit Corporation, ⅝ percent notes of series D, due Aug. 1, 1941, dated and bearing interest from Aug. 1, 1939, fully and unconditionally guaranteed both as to interest and principal by United States, which guaranty is expressed on face of each note, exempt both as to principal and interest from all Federal, State, municipal, and local taxation (except surtaxes, estate, inheritance, and gift taxes).