Institution guide

The federal TSP

No tickers, no brokerage, five lettered funds. The Thrift Savings Plan is among the cheapest retirement plans in existence, and it contains one holding — the G Fund — with no equivalent available to anyone outside it.

Federal & military ~0.06% net G Fund is unique

U.S. stocks International Bonds

An example 60/20/20 mix. Choose your own →

The five funds

Verify before you buy. Expense ratios and index methodologies change, and the figures on this page were compiled in early 2026. Every fund name below links to the provider's own page — check the current number there. A tenth of a basis point will not change your life, but a fund quietly changing what it tracks might.

What each letter actually holds
Fund	Holds	Role in a three-fund build
C Fund	S&P 500 — U.S. large-cap	U.S. stocks, the large-cap portion
S Fund	Dow Jones U.S. Completion — everything U.S. that is not in the S&P 500	U.S. stocks, the small- and mid-cap portion
I Fund	International developed and emerging markets, excluding China and Hong Kong	International stocks
F Fund	Bloomberg U.S. Aggregate Bond — the standard total bond market	Bonds, conventional version
G Fund	Special-issue Treasury securities available only to the TSP	Bonds, with no interest-rate risk

TSP expenses are charged as net administrative and investment costs rather than a published expense ratio per fund. They have historically sat in the range of roughly 0.05% to 0.06% — extremely low, but no longer the lowest available anywhere. Current figures are published on tsp.gov.

Building the three sleeves

U.S. stocks: C plus S, roughly four to one

Neither fund alone is the total U.S. market. The S&P 500 is about 80% of U.S. market value; the completion index is the remaining fifth. Holding them at approximately 80% C and 20% S reproduces a total-market fund closely. Anywhere from 80/20 to 85/15 is within the noise, and some people simply hold C alone — a defensible large-cap tilt, but not the same thing as owning the market.

International: the I Fund, with a caveat

The I Fund's benchmark was broadened in 2024 to an all-country ex-U.S. index that includes emerging markets and small caps but deliberately excludes China and Hong Kong. That makes it much better than its old developed-markets-only benchmark, and still not quite a total international fund. If you hold international elsewhere, you may want to account for the missing exposure there — or simply accept it as a considered policy choice.

Bonds: G rather than F, usually

This is the genuinely interesting decision in the TSP, and it has no analogue in a private account.

The G Fund cannot lose value. It holds special-issue Treasury securities created for the TSP alone. The share price never declines — it only accrues interest, at a rate tied to the average yield on medium- and long-term Treasuries. You collect a long-bond yield while carrying short-bond risk, which is not a trade available in any market.

What that means in practice. In 2022, when rising rates gave the total bond market its worst year in modern history and the F Fund fell with it, the G Fund simply kept accruing. Many long-time TSP investors use G as their entire bond allocation for exactly this reason.

The argument for keeping some F. The F Fund can post capital gains when rates fall, which the G Fund structurally cannot. If you want bonds that rally during a deflationary shock — the classic reason to hold them alongside stocks — some F has a role. A 50/50 split of the bond sleeve is a reasonable compromise; G alone is the more common answer.

Worked example

An 80/20 stock-to-bond portfolio with 30% of stocks international, translated into TSP contribution percentages.

Target 56% U.S. stocks · 24% international · 20% bonds
Sleeve	TSP fund	Allocation	Working
U.S. stocks	C Fund	45%	80% of the 56% U.S. sleeve
U.S. stocks	S Fund	11%	20% of the 56% U.S. sleeve
International	I Fund	24%	30% of the 80% stock allocation
Bonds	G Fund	20%	the whole bond sleeve, no rate risk

Use the allocation tool to pick your own stock-to-bond split, then apply the same arithmetic: multiply the U.S. sleeve by 0.8 for C and 0.2 for S.

TSP mechanics that trip people up

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Contribution allocation and interfund transfers are different things

Changing your contribution allocation directs future paycheques. Rebalancing what you already hold requires a separate interfund transfer. Changing one does not change the other, and assuming otherwise is the most common TSP mistake.

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Capture the full match first

Under FERS the government matches contributions up to 5% of salary. Contributing less than 5% declines part of your compensation. No allocation decision on this page comes close to mattering as much.

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L Funds are the automatic option

The Lifecycle funds are pre-mixed C/S/I/F/G portfolios that get more conservative over time. If you would rather not manage the split yourself, an L Fund is a perfectly good choice — not a lesser one.

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The mutual fund window rarely earns its fees

It opens up thousands of outside funds, wrapped in annual and per-trade charges that undo the TSP's main advantage. The five core funds already build a complete portfolio.

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Roth and traditional are a separate axis

The TSP offers both. That choice is about your tax rate now versus in retirement, and it is independent of which funds you hold.

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Think of the TSP as one part of a whole

If you also hold an IRA, treat both accounts as a single portfolio. Bonds in the TSP's G Fund and stocks in the IRA is often a sensible arrangement.

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