Key Takeaways
- The Thrift Savings Plan offers five core funds and eleven Lifecycle (L) Funds, 16 options in total.
- TSP net expense ratios run about 0.05%, around 5 cents per $100 invested.
- As of December 31, 2024, the TSP held roughly $963 billion across about 7.2 million participants.
- The C Fund tracks the S&P 500 Index, which has averaged roughly 10% per year over the long run.
- The I Fund now tracks the MSCI ACWI IMI ex USA ex China ex Hong Kong Index, no longer the MSCI EAFE index.
- The Mutual Fund Window requires transferring at least $10,000 and caps window holdings at 25% of your total TSP balance.
- In 2026 the combined TSP elective-deferral limit is $24,500.
TSP Funds by the Numbers
Figures reflect Thrift Savings Plan and IRS data for 2026 cited in this article.
The TSP funds are the investment choices inside the federal Thrift Savings Plan: five individual core funds (G, F, C, S, and I) plus eleven Lifecycle (L) target-date funds built entirely from those five. This guide breaks down each fund one by one, what it holds, the index it tracks, and its risk level, then covers the Roth versus traditional TSP wrapper that sits on top of the same menu.
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The Thrift Savings Plan offers five core funds and eleven Lifecycle funds. The core funds are G (short-term U.S. Treasury securities issued to the TSP), F (a broad U.S. bond index), C (the S&P 500), S (U.S. small and mid cap stocks), and I (international developed markets). The eleven L Funds blend those five into a single professionally rebalanced portfolio tied to a target date.
What are the TSP funds?
The TSP funds are the 16 investment options in the Thrift Savings Plan: five individual core funds and eleven Lifecycle (L) Funds. The five core funds (G, F, C, S, and I) each track a single asset class and index. The eleven L Funds are pre-built blends of those five that auto-rebalance toward a more conservative mix as a chosen target date approaches.
The Thrift Savings Plan is the defined-contribution retirement plan for federal employees and uniformed-service members, similar to a private-sector 401(k). As of December 31, 2024, it held roughly $963 billion in assets across about 7.2 million participants, making it one of the largest retirement plans in the world.
Every dollar you contribute goes into one or more of these funds based on your contribution allocation. You choose the funds; the wrapper (Roth or traditional) is a separate tax decision layered on top. For the broader plan mechanics, see our general explainer on what a Thrift Savings Plan is and the full resource hub for federal employees.
One feature worth stating up front: TSP funds carry net expense ratios of roughly 0.05% (around 5 cents per $100 invested), among the lowest of any retirement plan. The L Funds add no markup over the underlying core funds they hold.
The quick-reference table
The table below summarizes the five core TSP funds: what each holds, the index it tracks, its risk-return profile, and the type of investor it tends to suit. The eleven L Funds are covered separately because each one is a blend of these five rather than a distinct asset class.
| Fund | What it holds | Index tracked | Risk / return | Best for |
|---|---|---|---|---|
| G Fund | Short-term U.S. Treasury securities specially issued to the TSP | No market index (rate set by law) | Lowest risk, lowest growth; principal never drops | Capital preservation, near-retirees |
| F Fund | U.S. government, corporate, and mortgage-backed bonds | Bloomberg U.S. Aggregate Bond Index | Low to moderate; carries interest-rate risk | Diversifying stock risk with bonds |
| C Fund | Large U.S. company stocks | S&P 500 Index | Higher risk, higher long-run return | Core equity growth |
| S Fund | U.S. small and mid cap stocks outside the S&P 500 | Dow Jones U.S. Completion Total Stock Market Index | Highest volatility among core funds | Growth-seekers with a long horizon |
| I Fund | International developed and emerging-market stocks | MSCI ACWI IMI ex USA ex China ex Hong Kong Index | Higher risk; adds currency exposure | International diversification |
The G Fund: how safe is it, really?
The G Fund invests in short-term U.S. Treasury securities specially issued to the TSP. It is the only fund where principal cannot lose value: the share price never drops, and interest is credited at a rate tied to medium and long-term Treasury yields. The tradeoff is the lowest long-run growth of any TSP fund, which means inflation can erode purchasing power over decades.
Because these securities are issued directly to the plan rather than traded on the open market, the G Fund is not exposed to the price swings that affect the F Fund. Many federal employees use it as the stable anchor of a portfolio or as a parking place near retirement. Over a long career, however, holding too much in the G Fund can leave a balance growing slower than inflation.
The F Fund: what bonds does it hold?
The F Fund tracks the Bloomberg U.S. Aggregate Bond Index, holding a broad mix of U.S. Treasury, government agency, mortgage-backed, and investment-grade corporate bonds. Unlike the G Fund, the F Fund can lose value: when interest rates rise, bond prices fall, so its share price fluctuates. It offers higher expected return than the G Fund in exchange for that interest-rate risk.
The F Fund is the plan’s way to own the total U.S. bond market in one option. It tends to move differently from stocks, which is why the L Funds pair it with the C, S, and I Funds. Investors who want more return than the G Fund provides, and who can accept moderate price swings, often use the F Fund for the fixed-income slice of a portfolio.
The C Fund: is this the S&P 500?
Yes. The C Fund tracks the S&P 500 Index, so it holds roughly 500 of the largest U.S. companies weighted by market value. It is the plan’s large-cap growth engine. The S&P 500 has returned about 10% per year on average over the long run, though individual years range widely from steep losses to strong gains. The C Fund carries meaningful short-term risk in exchange for that long-run growth.
The C Fund is the single most widely used equity fund in the plan. Because it holds household-name companies, its returns closely follow the headlines you hear about the U.S. stock market. Younger participants with decades until retirement often weight heavily toward the C Fund, accepting down years in exchange for higher expected compounding over time.
The S Fund: what does “small cap” mean here?
The S Fund tracks the Dow Jones U.S. Completion Total Stock Market Index, which holds essentially every publicly traded U.S. stock outside the S&P 500: mid cap and small cap companies. Paired with the C Fund, it gives you the entire U.S. stock market. The S Fund is more volatile than the C Fund because smaller companies swing harder in both directions.
Think of the S Fund as the “everything else” of U.S. stocks. Many federal investors hold the C and S Funds together in roughly market-weight proportion (often around 4 parts C to 1 part S) to own the full domestic market. The higher volatility rewards patience: over long periods small and mid caps have historically added return, but they can lag large caps for years at a time.
The I Fund: which international index does it track now?
The I Fund tracks the MSCI ACWI IMI ex USA ex China ex Hong Kong Index. This is a critical accuracy point: the I Fund NO LONGER tracks the old MSCI EAFE index. The plan transitioned the I Fund to this broader benchmark, which now includes developed and emerging markets and small caps, while excluding China and Hong Kong. Many cached articles and Wikipedia still cite EAFE, which is outdated.
The practical effect: the I Fund gives broader international coverage than it did under EAFE, spanning more countries and company sizes. It adds diversification away from the U.S. market and introduces currency exposure, since it holds foreign-currency-denominated stocks. International returns can diverge sharply from U.S. returns in either direction, which is exactly why the L Funds include a slice of the I Fund.
What is a TSP Lifecycle (L) Fund, and should I just use one?
A TSP Lifecycle (L) Fund is a professionally managed blend of the five core funds tied to a target retirement date. There are eleven L Funds, ranging from L Income (for those already withdrawing) to L 2070. Each one automatically rebalances every quarter, shifting gradually from stocks toward the G and F Funds as its target date nears. L Funds add no fee beyond the underlying core funds.
The idea is one-decision investing: you pick the L Fund closest to the year you expect to need the money, and the plan handles the asset mix and rebalancing for you. A newly hired federal employee who does not choose their own allocation is automatically defaulted into the age-appropriate L Fund. L Income is the exception to the glide path; it holds a steady conservative mix designed for participants who are already taking distributions.
For many participants, a single L Fund is a reasonable complete portfolio. Investors who want to control their own stock-to-bond ratio, or who blend an L Fund with a separate G Fund position, may prefer the individual core funds instead.
Which TSP fund is safest, and which makes the most money?
The G Fund is the safest TSP fund: its principal never drops. Over the long run the C and S Funds have historically produced the highest returns, with the C Fund tracking the S&P 500’s roughly 10% long-run average. The risk-return ladder runs from lowest to highest as: G, then F, then I, then C, then S. Higher expected return always comes with larger short-term swings.
There is no single “best” fund; the right mix depends on your time horizon and tolerance for volatility. A common framework:
- Long horizon (decades to retirement): heavier weight to C, S, and I for growth.
- Medium horizon: a balanced blend, which is what the dated L Funds provide automatically.
- Short horizon or in retirement: more weight to G and F to protect principal against near-term losses.
As you approach retirement, sequence-of-returns risk (a large loss in the first few withdrawal years) becomes a central concern, which is one reason the L Funds and many investors shift toward the G and F Funds over time.
Roth vs. traditional TSP: does it change which funds I pick?
No. Roth versus traditional is a tax-wrapper choice, not a fund choice. The same G, F, C, S, I, and L menu is available in both. Traditional TSP contributions are pre-tax and taxed on withdrawal; Roth TSP contributions are after-tax and grow tax-free. You can split contributions between both. In 2026 the combined elective-deferral limit is $24,500.
This is the piece most fund explainers skip. Choosing the C Fund does not commit you to Roth or traditional; you decide the wrapper separately. The trade is tax-now versus tax-later. Roth TSP tends to favor those who expect to be in the same or a higher tax bracket in retirement, while traditional favors those expecting a lower future bracket.
A related planning move is a Roth conversion, which shifts traditional (pre-tax) dollars into a Roth account and pays the tax now to secure tax-free growth later. Federal employees weighing this should read our overview of the TSP Roth conversion decision, our Roth conversion service, and guidance on how much to convert. Timing matters too: a conversion is taxable ordinary income, is irreversible, and must be completed by the December 31 conversion deadline. Because large conversions can affect other thresholds, review the Net Investment Income Tax, the break-even math, and how Roth balances interact with required minimum distributions, which begin at age 73 (age 75 for those born in 1960 or later).
What about the Mutual Fund Window?
The Mutual Fund Window is the TSP’s optional “sixth choice,” letting participants invest a portion of their balance in thousands of outside mutual funds. It carries extra fees the core funds do not: an annual administrative fee, an annual maintenance fee, and per-trade charges, plus each fund’s own expense ratio. It also has minimums and caps, and most participants can safely skip it.
To use the window, you generally must transfer at least $10,000, keep at least a minimum balance in the core TSP, and you cannot hold more than 25% of your total TSP balance in the window. Between the added fees and the loss of the plan’s very low expense ratios, the window rarely improves outcomes for typical investors. The five core funds and the L Funds cover the major asset classes most retirement savers need.
How do I check or change my TSP fund allocation?
You manage TSP funds through your account at tsp.gov or the TSP mobile app. There are two distinct actions: a contribution allocation, which directs how your FUTURE contributions are invested, and an interfund transfer (now called a fund reallocation or fund transfer), which moves money already in your account. Changing one does not automatically change the other, so update both if you want a full shift.
The practical steps:
- Log in to your account at tsp.gov or the app.
- Set your contribution allocation to change where new payroll contributions go.
- Use a reallocation to change the mix of your existing balance, or a fund transfer to move money into or out of a specific fund.
- Confirm both future contributions and current balance reflect your intended mix.
Reviewing your allocation periodically, especially as retirement nears, helps keep your risk level aligned with your time horizon.
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Frequently asked questions
What are the 5 TSP funds?
The five core TSP funds are the G Fund (short-term U.S. Treasury securities issued to the TSP), the F Fund (Bloomberg U.S. Aggregate Bond Index), the C Fund (S&P 500), the S Fund (Dow Jones U.S. Completion Total Stock Market Index of small and mid caps), and the I Fund (MSCI ACWI IMI ex USA ex China ex Hong Kong Index). The eleven L Funds are blends of these five.
Which TSP fund is the safest?
The G Fund is the safest TSP fund. It invests in short-term U.S. Treasury securities specially issued to the plan, and its principal cannot lose value: the share price never drops. The tradeoff is the lowest long-run growth of any TSP fund, which means it may not keep pace with inflation over a multi-decade career.
Which TSP fund makes the most money?
Over the long run the stock funds, chiefly the C Fund and S Fund, have produced the highest returns, though with the largest short-term swings. The C Fund tracks the S&P 500, which has averaged roughly 10% per year historically. Past performance is not a guarantee; higher expected return always comes with a real chance of losses in any given year.
What does the C Fund track?
The C Fund tracks the S&P 500 Index, holding about 500 of the largest U.S. companies weighted by market value. It is the plan’s large-cap U.S. equity option and its primary long-term growth engine. Its returns closely follow the broad U.S. stock market that headlines describe, including both strong gains and periodic sharp declines.
What is the difference between the C Fund and the S Fund?
The C Fund holds large U.S. companies in the S&P 500, while the S Fund holds the small and mid cap companies outside the S&P 500, tracking the Dow Jones U.S. Completion Total Stock Market Index. Held together they cover the entire U.S. stock market. The S Fund is more volatile because smaller companies tend to swing harder in both directions.
What is a TSP Lifecycle (L) Fund?
A TSP Lifecycle (L) Fund is a ready-made blend of the five core funds tied to a target retirement date. There are eleven, from L Income to L 2070. Each rebalances quarterly and shifts automatically from stocks toward the G and F Funds as its date nears. L Funds charge no fee beyond the underlying core funds they hold.
What is the default TSP fund for new employees?
A newly hired federal employee who does not choose their own investments is automatically defaulted into the age-appropriate Lifecycle (L) Fund, the one whose target date is closest to when they would reach retirement age. This gives new enrollees a diversified, auto-rebalancing portfolio by default. Participants can change their allocation at any time at tsp.gov.
Should I choose Roth or traditional TSP?
Roth versus traditional TSP is a tax choice, not a fund choice, and both use the same G, F, C, S, I, and L menu. Traditional contributions are pre-tax and taxed on withdrawal; Roth contributions are after-tax and grow tax-free. Roth often fits those expecting the same or higher future tax brackets. Many investors split between both; a qualified professional can help weigh your situation.
