TSP is a retirement benefit offered to Federal employees. It is similar to 401(k) plans available to many private-sector employees. The purpose of TSP is to give you the ability to participate in a long-term savings and investment plan. The Federal Retirement Thrift Investment Board administers TSP and contracts with various private-sector companies to provide recordkeeping services.
If you are covered by the Federal Employees Retirement System (FERS), TSP is an integral part of the retirement package, along with your FERS basic annuity and Social Security. TSP is especially important to FERS employees because the formula used to compute a FERS basic annuity is less generous than the formula used to compute a Civil Service Retirement System (CSRS) annuity.
If you are covered by CSRS, TSP is a supplement to your CSRS annuity.
Regardless of your retirement system, participating in TSP can significantly increase your retirement income, but starting early is important. Contributing early gives the money in your account more time to increase in value through the compounding of earnings.