The Thrift Savings Plan, or TSP, is the retirement savings program built for federal civilian employees and members of the uniformed services. It functions like a 401(k) — pre-tax or Roth contributions, employer matching, a menu of funds — but with a narrower fund lineup and famously low fees. If you are new to federal service or just now paying attention to your benefits, the TSP is usually the single best place to start.
What changed in 2026
- Contribution limits rise with inflation adjustments each year — check the current annual figure before assuming last years cap still applies.
- Catch-up contributions for savers 50 and older continue to use the "spillover" method, meaning you do not need to elect a separate catch-up contribution — regular contributions above the standard limit automatically spill into catch-up status.
- The Roth TSP option remains available alongside traditional, and more agencies are defaulting new hires into an auto-enrollment percentage that has crept upward in recent years — check your own paycheck elections rather than assuming the default fits you.
How TSP matching works
Most FERS (Federal Employees Retirement System) employees get an automatic 1 percent agency contribution regardless of whether they contribute anything themselves, plus a match on the first 5 percent of pay you contribute. Put together, contributing at least 5 percent of your own pay typically captures the full match — leaving money on the table below that threshold is one of the more avoidable mistakes in federal benefits.
Uniformed service members under the Blended Retirement System have a similar structure, though the specifics of vesting and match timing differ from civilian FERS rules, so service members should check their branchs summary plan description.
The fund lineup
The TSP keeps its options deliberately simple:
- G Fund — government securities, essentially no default risk, low long-run return.
- F Fund — bond index fund.
- C Fund — large-cap US stock index, tracks a broad market benchmark.
- S Fund — small and mid-cap US stock index.
- I Fund — international stock index.
- L Funds — lifecycle funds that blend the above based on a target retirement date and auto-rebalance over time.
| Fund |
Type |
Typical role |
| G Fund |
Government securities |
Capital preservation |
| F Fund |
Bond index |
Ballast, income |
| C Fund |
Large-cap US stocks |
Core growth |
| S Fund |
Small/mid-cap US stocks |
Growth, higher volatility |
| I Fund |
International stocks |
Diversification |
| L Funds |
Target-date blend |
Hands-off allocation |
TSP vs a private-sector 401(k)
The TSP usually wins on cost — its expense ratios are a fraction of what many corporate 401(k) plans charge for comparable index exposure. What it lacks is breadth: no sector funds, no individual stock options, and a narrower international selection than many private brokerages offer. For most savers that narrowness is a feature, not a bug, since it removes the temptation to overtrade.
Common TSP mistakes
- Not contributing enough to get the full match — this is the closest thing to guaranteed return in the plan.
- Leaving money in the G Fund for decades out of excess caution, which can badly lag inflation over a long career.
- Ignoring the plan after separating from federal service. You can typically leave funds in the TSP after leaving government work, and the low fees often make that worth doing rather than rolling immediately into a pricier IRA.
FAQ
Can I lose my TSP contributions if I leave federal service early?
Your own contributions are always yours. Agency automatic and matching contributions typically vest after a set period of service — check the current vesting schedule for your position type.
Is the Roth TSP better than traditional?
It depends on whether you expect a higher or lower tax rate in retirement than today. Many federal employees split contributions between both to hedge that uncertainty. This is general information, not personalized tax advice.
Can I roll an old 401(k) into my TSP?
Yes, in most cases you can roll eligible balances into the TSP, taking advantage of its low fees, though you should confirm the receiving rules with the TSP administrator first.
What happens to my TSP after I retire?
You can leave it invested, take withdrawals, or roll it into an IRA. Each path has different tax and flexibility tradeoffs worth reviewing with a professional.
Where to go next
For more on employer-sponsored retirement plans, see what a 401(k) match actually means, how a 457(b) plan works, and what a defined benefit plan is.