TSP vs 401(k): Fees, Matching, Eligibility, and Which Factors Matter
One comparison of the Thrift Savings Plan and private-sector 401(k) plans: who can use each, how matching works, how fees and investments differ, and how to think about the choice without picking a universal winner.
PayAtlasUSA Team
7 min read
How to use this guide
This article explains concepts and typical rules. Dollar figures that come from PayAtlas data files are labeled as such. Confirm time-sensitive amounts with the official source before relying on them.
Quick answer
The Thrift Savings Plan (TSP) is the defined-contribution retirement savings plan for eligible federal employees and members of the uniformed services. A 401(k) is an employer-sponsored plan common in the private sector (and some other non-federal employers). Both let workers defer pay into investments, often with a Roth or traditional tax treatment. They differ in who can join, how employer money works, investment menus, fees, and some distribution rules.
This page consolidates comparison intent (TSP vs 401(k), fees, matching, “which is better”) into one guide. It is educational, not tax, legal, or investment advice.
Key takeaways
- TSP eligibility is a federal / uniformed-service status question. A state teacher or private employee generally uses a different plan type.
- For many FERS civilians, failing to contribute enough to capture the full agency match is leaving compensation on the table — similar in spirit to not taking a 401(k) match, but the formula is specific to FERS/TSP.
- TSP’s core funds are a small, indexed-style menu. A 401(k) may offer more funds, target-date series, or brokerage windows, sometimes at higher cost.
- IRS elective deferral limits are time-sensitive. Look up the current year on IRS.gov and TSP.gov rather than memorizing an old ceiling.
- “Better” depends on match, vesting, fees, and career path, not on a slogan.
What each plan is
TSP
TSP is administered for covered participants with a standard set of funds (commonly discussed as G, F, C, S, I, and Lifecycle L funds) plus, for those who elect it, a mutual fund window with additional rules and fees. Civilian and uniformed-service accounts can have different contribution sources (for example, tax-exempt combat-zone pay for some members).
TSP sits beside a defined-benefit pension for many FERS employees. It is not a replacement for FERS annuity math, and it is not GS pay.
401(k)
A 401(k) is a plan an employer designs within IRS and ERISA rules (private sector). The employer chooses the recordkeeper, matching formula, vesting, and investment lineup. Two 401(k) plans can be less alike than TSP is to a typical large-plan 401(k).
Public schools more often use 403(b) or 457(b) and a state pension. Do not call those “the TSP.”
Eligibility
| Topic | TSP | Typical 401(k) |
|---|---|---|
| Who | Covered federal civilians and uniformed services | Employees of that private (or other eligible) employer |
| Portable when you leave | Account can stay in TSP or be rolled per rules | Often rolled to IRA or new employer plan |
| State employees | Not by virtue of state employment | Uncommon; other plan types more likely |
If you hold a GS job, your retirement coverage (FERS, FERS-RAE, FERS-FRAE, CSRS, etc.) changes automatic and matching TSP contributions. Check the SF-50, not a blog.
Contributions and matching
Both plans usually allow:
- Traditional (pre-tax) elective deferrals
- Roth elective deferrals (if the plan offers Roth)
Employer money differs.
FERS (typical civilian pattern, confirm for your appointment):
- Agency automatic 1% of basic pay (even if you contribute 0%, once eligible)
- Agency matching on the first 5% of your contribution, structured so that contributing 5% is the usual way to receive a full 5% agency total (1% automatic + 4% match)
Uniformed services / BRS: matching exists under BRS rules and service-commitment conditions. Legacy retirement systems may have little or no match. See the military pay guide for how BRS fits next to basic pay.
401(k): formulas vary — 50% match on 6%, 100% on 4%, none, profit sharing, safe harbor, and so on. Vesting schedules can mean you forfeit unvested employer amounts if you leave early. TSP agency automatic and matching contributions for FERS civilians are generally not subject to the same private-sector vesting cliff, which is a structural difference people miss.
Limits: IRS section 402(g) elective deferral limits (and catch-up provisions) apply. They change. This article intentionally does not freeze a dollar cap in the heading; use the current IRS page linked in Official Sources.
Investments and fees
TSP core funds are built as broad, low-cost options (government securities, bonds, large U.S. stocks, small/mid U.S. stocks, international stocks, and lifecycle mixes). That simplicity is a feature for people who do not want a 40-fund menu. It is a limitation for people who want individual stocks or niche sectors in the core account (the mutual fund window is a separate, fee-bearing choice).
401(k) menus range from excellent institutional index funds to expensive actively managed funds with revenue sharing. The Form 404a-5 fee disclosure is the document to read.
Expense ratios compound. A 0.40% gap on a large balance over decades is economically meaningful. That still does not make TSP “always better” if the 401(k) match is richer, or if you need a brokerage window the TSP core does not provide.
Loans and withdrawals
Both plan types may allow loans and hardship or in-service withdrawals under different rules. TSP loan and withdrawal rules are published on TSP.gov and have changed over time (including post-SECURE Act and TSP modernization). 401(k) loan availability is plan-specific.
In-service access, Roth conversion features, and required minimum distributions in retirement should be checked against current official publications. Do not use a forum post from five years ago.
When you leave federal service, TSP rollover options exist; when you leave a private employer, 401(k) rollover options exist. Each rollover has tax and creditor-protection implications. Get professional advice for a large balance.
Worked matching example
Assumptions (illustrative only): FERS employee, basic pay $76,463 (GS-12 Step 1 base from the PayAtlas GS table — not locality-adjusted, and not your salary if you have locality pay). The employee contributes 5% of that basic pay to TSP.
- Employee deferral: 0.05 × $76,463 = $3,823.15 per year (example)
- Agency automatic 1%: $764.63
- Agency match on a typical 5% contribution pattern: $3,058.52 (4% of basic pay)
- Combined agency money in this sketch: $3,823.15 (5%)
If the same person instead contributed 0%, many FERS employees would still receive the 1% automatic contribution only, and would forgo the match. That is a compensation decision, not a moral judgment.
A private 401(k) example cannot use one national formula. If an employer matches 100% on the first 4% of a $76,463 salary, employer money would be $3,058.52 in that sketch, with different vesting. Label every comparison with the actual policy.
If pay includes locality, FERS TSP percentages generally apply to basic pay as defined for retirement (which typically includes locality). Use your LES/earnings statement, not the base-only table, for a personal estimate. The GS Pay Calculator helps estimate locality-adjusted GS pay; it is not a TSP contribution engine.
Advantages and limitations
TSP — often attractive because
- Very low core-fund costs
- Simple default menu
- Standardized FERS matching for many civilians
- Portable within the federal/uniformed ecosystem
TSP — limitations
- You must be eligible; it is not a public IRA alternative for everyone
- Core menu is small
- Some features (window, withdrawals) have extra rules and costs
- Uniformed-service matching is not identical to FERS civilian matching
401(k) — often attractive because
- Employer design can include generous matches or profit sharing
- Broader investment menus or brokerage windows in some plans
- Familiar to private-sector households
401(k) — limitations
- Fees and fund quality vary widely
- Vesting can claw back employer money
- No access if you are a federal employee without a private-plan job
Common mistakes
- Calling TSP “a 401(k)” in legal or tax documents. They are cousins, not the same plan.
- Contributing 3% to FERS TSP and assuming the match is maxed. The usual full-match contribution is 5% of basic pay for many FERS employees.
- Using last year’s IRS limit.
- Comparing TSP G Fund to a 401(k) stable-value fund without reading both prospectuses.
- Ignoring Roth vs. traditional as if the wrapper did not matter for future tax brackets.
- Assuming state workers have TSP.
- Rolling out of TSP automatically without comparing fees in the destination IRA.
Who this is relevant for
- FERS and BRS participants deciding a deferral rate
- Dual-career households with one federal and one private job
- Applicants comparing a GS offer’s benefits paragraph to a corporate offer
- Service members learning how BRS and TSP interact with military pay
Related PayAtlasUSA resources
- GS Pay Scale — how the salary that TSP percentages apply to is built
- Military pay charts — allowances vs. taxable basic pay next to TSP
- GS Pay Calculator
- TSP.gov — elections, fund details, and current rules
- IRS contribution limits