All TSP participants must have an added security feature known as "two-step authorization" enabled on their accounts or they will not be able to log on to their account. And no, two-step authorization has nothing to do with boot-scooting your way across a barroom floor to country music.
Thrift Savings Plan (TSP) is a defined contribution plan for United States civil service employees and retirees as well as for members of the uniformed services any Login problems visit TSP Login