It is a Federal benefit.
The Thrift Savings
Plan (TSP) is a tax-deferred 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. By participating in the
TSP, Federal employees have the opportunity to save part of their income for
retirement, receive matching agency contributions, and reduce their current
taxes.
From
<https://www.opm.gov/retirement-services/my-annuity-and-benefits/thrift-savings-plan/>
