TSP Fund Allocation Guide for Federal Employees (2026)
Most federal employees set their TSP allocation once — at enrollment — and never revisit it. Some leave everything in the G Fund for 30 years. Others pick an L Fund and forget about it. This guide explains what each fund actually is, how to think about allocation across your career, and the specific mistakes that cost federal employees the most over time.
- 5 individual funds: G, F, C, S, I — plus 10 Lifecycle (L) funds
- Expense ratio: 0.034–0.039% depending on fund — among the lowest of any retirement plan in the U.S.1
- G Fund 1-year return (through April 2026): 4.44%1
- 2026 elective deferral limit: $24,500 (catch-up age 50–59: +$8,000; super catch-up age 60–63: +$11,250)
- Agency match: automatic 1% + match up to 4% more = 5% maximum. Must contribute ≥5% to capture full match.
The five individual funds
G Fund — Government Securities Investment Fund
The G Fund invests in short-term U.S. Treasury securities specially issued to the TSP. It earns the long-term Treasury rate without the duration risk of holding long-term bonds — a structural advantage that exists nowhere else. Your principal and accrued interest are guaranteed by the U.S. government and cannot decline in nominal value.2
1-year return (through April 2026): 4.44%. The G Fund rate is recalculated monthly based on the weighted average yield of all outstanding Treasury securities with 4+ years to maturity.
Who it's for: retirees managing sequence-of-returns risk, employees within 1–2 years of retirement who can't afford a drawdown, or anyone needing a cash-equivalent bucket for near-term income needs.
Who it hurts: employees with 10+ years to retirement who hold a large G Fund balance. See the G Fund trap below.
F Fund — Fixed Income Index Fund
The F Fund tracks the Bloomberg U.S. Aggregate Bond Index — a broad mix of U.S. investment-grade bonds including Treasuries, mortgage-backed securities, and corporate bonds. Unlike the G Fund, the F Fund can lose value when interest rates rise (duration risk: approximately 6-year duration, so a 1% rate rise → roughly 6% price drop).
Who it's for: employees wanting traditional bond exposure for diversification. More return potential than G Fund over long periods; more volatility. Generally a secondary allocation after G Fund for fixed-income exposure.
C Fund — Common Stock Index Fund
The C Fund tracks the S&P 500 index — 500 large U.S. companies. This is your primary growth engine. Historically the C Fund has returned approximately 10–11% annually over multi-decade periods, with significant short-run volatility.
Who it's for: virtually all federal employees with more than 5 years to retirement. The C Fund should typically be the largest equity holding in your TSP at accumulation stage.
S Fund — Small Cap Stock Index Fund
The S Fund tracks the Dow Jones U.S. Completion Total Stock Market Index — approximately 4,500 U.S. companies not in the S&P 500 (mid-caps and small-caps). Historically produces higher long-run returns than C Fund with meaningfully higher volatility. A C Fund + S Fund combination gives you exposure to the total U.S. stock market.
Who it's for: employees comfortable with volatility who want broad U.S. market exposure. Typically held as a satellite position (10–20%) alongside a larger C Fund allocation.
I Fund — International Stock Index Fund
The I Fund underwent a major benchmark change in October 2024. It now tracks the MSCI All Country World ex USA ex China ex Hong Kong Investable Market Index — a significant expansion from the prior MSCI EAFE (Europe, Australasia, Far East) index.3
The new index covers more than 5,000 companies across 40+ developed and emerging market countries (excluding China and Hong Kong per the TSP board's decision). This replaced the old EAFE index that covered roughly 55% of non-U.S. market cap — the new index covers approximately 90%.
What changed for participants: the I Fund now includes small-cap and emerging-market exposure it previously lacked. Volatility will be somewhat higher than the legacy EAFE-based I Fund. The diversification benefit is greater.
Who it's for: employees who want international diversification alongside U.S. equity exposure. Most allocation frameworks suggest 10–20% international for diversification without overweighting currency risk.
The G Fund trap: the most common TSP mistake
The G Fund feels safe. It never goes down in nominal terms. For many federal employees who lived through 2001, 2008, or 2020, that no-loss guarantee is deeply appealing. But the G Fund trap costs federal employees real money over careers.
GS-12 employee, age 35, contributes $12,000/year to TSP for 30 years to age 65:
- 100% G Fund at 4% average annual return: ~$672,000
- 80% C Fund / 20% G Fund at blended ~8.5% average annual return: ~$1,530,000
- Difference: ~$858,000 — from choosing "safety" 30 years before needing it
Note: illustrative only. Past returns don't guarantee future results. Long-run S&P 500 annualized return is approximately 10% nominal; blended return assumes lower expected future returns.
The G Fund trap is especially costly because the G Fund does not keep pace with inflation over long periods. The G Fund's 10-year annualized return is 2.76% as of April 2026 — below the average CPI over the same period. Holding 100% G Fund in your 30s and 40s is not being conservative; it's a guaranteed real-money loss at a slow rate.
The G Fund is appropriate as a large allocation only when you're within 2–3 years of retirement, managing sequence-of-returns risk in early retirement, or have specific short-term distribution needs. For accumulation, it should be a small ballast, not a default.
Lifecycle (L) funds: when they work and when they don't
L Funds are target-date funds built from the five individual funds above, automatically shifting toward conservative allocations as the target date approaches. They exist from L Income (most conservative) through L 2065 (most aggressive). If you have zero interest in managing your TSP, picking an L Fund near your expected retirement year is a reasonable default.
The L Fund mismatch problem: L Funds are designed around a retirement date, not a death date. If you retire at 57 and expect to draw TSP through age 85, your real investment time horizon is 28 years. An L 2030 fund — chosen because it matches your 2029 retirement — will be heavily conservative (mostly G and F Fund) starting the year you retire, when your money actually needs decades more to compound.
If you use L Funds, consider picking 1–2 rungs more aggressive than your retirement year (e.g., L 2050 instead of L 2030 if you retire in 2030) to account for your actual spending horizon and guaranteed income floor.
Allocation by career stage
These are general frameworks — your FERS annuity income floor, risk tolerance, and specific timeline will shift the right answer. Use these as starting points, not prescriptions.
Stage 1: Early career (20+ years to retirement)
Your primary objective is growth. You have time to recover from any market downturn, and your human capital (future career earnings) is your largest asset — dwarfing your TSP balance. Market crashes at this stage are a gift: lower prices, more shares purchased.
| Fund | Suggested range | Rationale |
|---|---|---|
| C Fund | 60–70% | Primary U.S. equity growth engine |
| S Fund | 15–20% | Small/mid-cap complement; higher long-run return potential |
| I Fund | 10–20% | International diversification; reduced correlation to U.S. market |
| G / F Fund | 0–10% | Minimal fixed income needed at this stage |
Stage 2: Mid-career (10–20 years to retirement)
Still primarily growth-oriented, but beginning to build a modest fixed-income buffer. The FERS match strategy matters most here — make sure you're capturing the full 5% agency contribution.
| Fund | Suggested range | Rationale |
|---|---|---|
| C Fund | 50–60% | Still the core growth driver |
| S Fund | 10–15% | Slightly reduced as volatility tolerance decreases |
| I Fund | 10–15% | Maintain international diversification |
| F Fund | 5–10% | Begin building bond buffer |
| G Fund | 5–10% | Stability ballast; avoid over-weighting |
Stage 3: Pre-retirement (1–5 years out)
Sequence-of-returns risk is now real. A significant market decline in your final 3–5 working years, combined with continuing withdrawals in early retirement, can permanently impair your TSP purchasing power. Begin shifting toward a more conservative posture — but don't go to 100% G Fund. If your FERS annuity covers most living expenses, you can stay moderately aggressive.
| Fund | Suggested range | Rationale |
|---|---|---|
| C Fund | 35–50% | Maintain growth for remaining 20–30 year retirement horizon |
| S Fund | 5–10% | Reduced; volatility more consequential near retirement |
| I Fund | 5–10% | Maintain but reduce international exposure |
| F Fund | 10–15% | Bond buffer for drawdown flexibility |
| G Fund | 20–35% | 2–3 years of TSP income need in stable bucket; no sequence risk |
Stage 4: In retirement / distribution phase
You're drawing from TSP. The bucket strategy works well here: hold 2–3 years of anticipated TSP income need in G Fund, enough to weather a prolonged downturn without forced selling of equities at depressed prices. The remainder can stay invested for the 20–30 year retirement horizon.
Critically: don't over-concentrate in G Fund in retirement if your FERS annuity + Social Security covers living expenses. If guaranteed income pays the bills, your TSP can remain meaningfully growth-oriented to protect purchasing power over a long retirement.
Worked example: GS-14 at 52 with $480,000 TSP
Profile: GS-14 step 8, DC area, age 52, planning to retire at 57 (MRA + 30 years service). FERS annuity will be approximately $46,500/yr. FERS supplement ≈ $15,000/yr until 62. TSP balance: $480,000. Current allocation: 100% G Fund (set at enrollment, never changed).
Problem: 100% G Fund at age 52 with 5 years to retirement and another 30 years of retirement ahead. Expected G Fund return: ~4.5% nominal. Expected inflation: ~2.5%. Real return: ~2%.
Suggested reallocation for this profile:
40% C Fund | 10% S Fund | 10% I Fund | 15% F Fund | 25% G Fund
Rationale: FERS annuity + supplement covers ~$61,500/yr — roughly 80–85% of a $75,000/yr lifestyle. TSP only needs to supply ~$13,500/yr (a 2.8% withdrawal rate on $480K) until Social Security starts. With guaranteed income covering baseline expenses, the TSP can remain ~60% equities to protect 30 years of purchasing power. G Fund bucket of 25% covers approximately 9 years of TSP income draws at the projected rate — far more stability than sequence-of-returns risk requires. Moving from 100% G to this mix could add meaningful long-run value while still dramatically reducing risk vs. a pure growth portfolio.
This is illustrative, not personalized advice. A federal-benefits specialist will model your specific FERS annuity, tax bracket, and Social Security timing before recommending an allocation.
Common TSP allocation mistakes
- 100% G Fund for decades. The most common and costly. See the G Fund trap section above.
- Picking an L Fund based on retirement date, not spending horizon. A 57-year-old retiring in 2026 who picks L Income or L 2025 is dramatically underinvested for a 30-year retirement. Consider L 2040 or L 2045 instead.
- Ignoring the S Fund entirely. Many federal employees know the C Fund and G Fund and skip the S and I Funds. The U.S. stock market is roughly 80% S&P 500 (C Fund) and 20% everything else (S Fund) by market cap. A C+S split gets you the full U.S. market.
- Not adjusting after the I Fund benchmark change. If you held I Fund pre-October 2024 expecting MSCI EAFE (developed markets only, excluding emerging markets), your fund now tracks a much broader index including small-caps and selective emerging markets. Your actual allocation has changed even if your percentage stayed the same. Review whether the new I Fund fits your allocation intent.
- Making allocation changes in a panic. Moving from C Fund to G Fund after a 20% drop locks in the loss and guarantees you'll miss the recovery. The G Fund rate won't compensate. Stay the course or rebalance systematically.
- Not capturing the full agency match. FERS employees who contribute less than 5% of basic pay are leaving free money behind. The 1% automatic agency contribution + 4% match = $7,250/year for a GS-14 at $145,000. Every year this isn't captured is a permanent loss.
When to get help with TSP allocation
TSP allocation interacts with FERS annuity timing, FERS supplement decisions, Roth conversion strategy in early retirement, IRMAA planning, and survivor annuity elections in ways that a fund-selection table can't fully capture. The right TSP allocation at 57 depends on:
- Your specific FERS annuity amount (how much guaranteed income you'll have)
- Whether you plan to file Social Security at 62, FRA, or 70
- Whether the FERS supplement bridge changes your TSP withdrawal needs in years 57–62
- Your expected tax bracket in retirement (to determine traditional vs. Roth balance)
- Your IRMAA exposure if TSP withdrawals push you above $109,000 MAGI4
A fee-only advisor specializing in federal employee benefits will model all of these together — not just the fund lineup in isolation. See our guide to choosing a financial advisor for federal employees if you're unsure how to find one.
Get matched with a federal benefits specialist
TSP allocation is just one piece. A fee-only advisor who specializes in federal employee benefits will model your full picture — FERS annuity, FERS supplement timing, Roth conversion window, and IRMAA exposure — alongside your fund allocation. Free match, no commissions, fee-only advisors only.
Sources
- Fund Information May 2026 — TSP.gov — G Fund 1-year return, administrative expense ratios by fund
- G Fund — The Thrift Savings Plan (TSP.gov) — fund structure, guaranteed principal/interest, rate calculation method
- I Fund benchmark index change complete — TSP.gov (October 2024) — transition from MSCI EAFE to MSCI ACWI IMI ex USA ex China ex Hong Kong
- IRS.gov — Medicare IRMAA thresholds 2026 — IRMAA first tier begins at $106,000–$109,000 MAGI for single filers
Fund return data and expense ratios verified against TSP.gov Fund Information (May 2026). Allocation frameworks are illustrative; they do not constitute personalized investment advice.