The TSP stands for Thrift Savings Plan, which is a defined contribution plan for United States civil service employees and retirees as well as for members of the uniformed services. It is a retirement savings and investment plan that offers Federal employees the same type of savings and tax benefits that many private corporations offer their employees under 401(k) plans. The TSP is administered by the Federal Retirement Thrift Investment Board, an independent agency. The retirement income you receive from your TSP account will depend on how much money you put into your account during your working years and the earnings accumulated over time. The TSP is one of three components of the Federal Employees Retirement System (FERS; the others being the FERS annuity and Social Security) and is designed to closely resemble the dynamics of private sector 401(k) and Roth 401k plans.