You Hit $500K in TSP. Here's How Your Strategy Should Change.

Last Updated: March 17, 2026 Reading Time: 10 min

Half a million dollars in your Thrift Savings Plan. You got here by doing the right things. The question now is whether those same moves still make sense.

On r/thriftsavingsplan, a thread asking "Why continue to contribute after hitting $500K?" pulled 104 upvotes and 203 comments. That is a lot of engagement for a retirement forum. Federal employees with large balances are genuinely wrestling with this. The short answer is: don't stop. The longer answer is that $500K is the point where the strategy needs to evolve from building the pile to managing what the pile is going to do to your taxes.

Here is what changes, what stays the same, and what to do next.

Key Takeaways

• Never stop contributing below the 5% that captures the full agency match. Stopping costs you real money every pay period.
• At $500K, the primary risk is no longer "do I have enough?" It is "will taxes eat my retirement?"
• A GS-14 with $1.2M in traditional savings at age 73 faces roughly $105,000 to $124,000 in taxable income per year before any discretionary spending.
• The 2026 Roth in-plan conversion (launched January 28, 2026) lets you start converting inside MyAccount with no IRA rollout required.
• Contribution waterfall: 5% to capture the match, then Roth IRA (or backdoor Roth), then max remaining deferrals, then taxable brokerage.

The One Thing That Never Changes

Before anything else, this is non-negotiable.

FERS gives you:

• 1% automatic agency contribution (you get this regardless)
• Dollar-for-dollar match on your first 3%
• 50-cent-per-dollar match on the next 2%

If you contribute 5% of your pay, the agency adds 5%. That is an immediate 100% return on the first 3% before the market does anything. No IRA, brokerage, or investment product on earth does that.

At a GS-13 Step 5 salary of roughly $110,000, the 4% matching contribution equals $4,400 per year. If you stop contributing to "diversify," you forfeit that $4,400 every single year. Stop contributing only if you want to pay extra tax and receive less retirement income.

What Shifts at $500K: The RMD Problem

At lower balances, the goal is simple: accumulate. At $500K, the math starts working against you in a specific way.

Nearly all of that $500K is sitting in traditional (pre-tax) contributions. Every dollar you add grows tax-deferred, which is good. But every dollar you eventually withdraw is fully taxed as ordinary income. At $500K growing at a modest 6%, you reach somewhere between $1M and $1.5M by retirement.

Under SECURE 2.0, required minimum distributions begin at age 73. The IRS forces you to withdraw a fixed percentage each year, whether you need the money or not.

The math at age 73:

• $1,000,000 / 26.5 (IRS distribution period) = $37,736 mandatory withdrawal
• $1,500,000 / 26.5 = $56,603 mandatory withdrawal

Stack that on top of your pension and Social Security. A GS-14 who retires at 62 with 30 years and a high-3 of $130,000 faces this income picture at age 73:

Income Source	Annual Amount	Taxable Portion
FERS pension (30 x 1.1% x $130,000)	$42,900	~95%
Social Security (estimated)	$22,000-$36,000	~85%
Traditional retirement account RMD (at $1.2M)	~$45,000+	100%
Total taxable income	$105,000-$124,000	All ordinary income

For married filing jointly, that lands squarely in the 22% bracket. For single filers, it approaches the 24% bracket. And that is before any discretionary spending from other accounts.

There is also the IRMAA problem. Medicare Part B and D surcharges kick in when your MAGI exceeds $109,000 (single) or $218,000 (MFJ) in 2026. A lot of federal retirees hit this threshold from involuntary required distributions they did not plan for. IRMAA Tier 1 alone adds roughly $900 to $1,200 per person per year in Medicare costs.

Both of these problems have the same fix: build Roth balances now, before retirement, so you have tax-free income to pull from later instead of forcing every dollar through ordinary income rates.

The Contribution Waterfall: Where New Money Should Go

Once you have the match locked in, here is how to think about the rest.

The first priority after capturing the match is a Roth IRA, not more traditional TSP. Why? Roth IRA has no required minimum distributions, ever. Roth balances inside the thrift plan are still subject to RMDs unless you roll them out to a Roth IRA after separation. Roth IRA also gives you more flexibility: you can withdraw contributions (not earnings) at any time, penalty-free, at any age, which matters if you retire before 59.5.

The 2026 Roth IRA limit is $7,500 (under 50) or $8,600 (50+). Direct contributions phase out at $153,000 (single) and $242,000 (MFJ). Most GS-14s and above are over these limits. For them, the backdoor Roth, contributing to a non-deductible traditional IRA and then immediately converting it, is fully available with no income cap. Watch the pro-rata rule if you have other pre-tax IRA balances.

After the Roth IRA is funded, max out the remaining TSP deferrals. In 2026: $24,500 for everyone, up to $32,500 if you are 50-59 or 64+, and up to $35,750 if you are 60-63 under the SECURE 2.0 "super catch-up." If you earned $145,000+ in 2025, your catch-up contributions must go to Roth anyway, starting this year.

At that point, if your traditional balance is already large relative to your projected retirement income, shift the elective deferrals toward Roth rather than traditional. You pay tax now at your working rate; withdrawals in retirement are tax-free.

Anything beyond that goes into a taxable brokerage: no contribution limits, full liquidity, and long-term capital gains rates on holdings you keep for a year or more. It is also a useful bridge account for the years between early retirement and when you start drawing Social Security at 70.

Use our TSP Calculator to model how these choices affect your projected balance and estimated taxes at withdrawal.

The Roth In-Plan Conversion: Your New Tool

On January 28, 2026, TSP launched Roth in-plan conversions inside MyAccount.

Before this, converting traditional TSP to Roth required rolling out to an IRA first. That added steps and complexity. Now you can convert any amount directly without leaving the plan. The converted amount is taxable as ordinary income in the year of conversion.

The reason this matters at $500K is the gap years.

If you retire at your minimum retirement age (57 with 30 years), your pension is coming in but Social Security has not started yet, and required distributions are still 16 years away. Your taxable income during that window is relatively low. It is the best window you will ever have to convert at a favorable rate.

Example:

• Retire at 57 with a $700,000 traditional balance
• FERS pension: $38,000/year
• Social Security: not yet
• RMDs: not until 73

During ages 57 to 73, converting $25,000 to $40,000 per year keeps you in the 12% to 22% bracket. Over 16 years, you convert $400,000 to $640,000 at a controlled tax cost. That is $400,000 to $640,000 that will never be forced out as ordinary income at 73.

One thing to know: conversions are irrevocable and add to taxable income the year you do them. A large conversion can accidentally push you into a higher bracket, make more of your Social Security taxable, or trigger IRMAA. Run the numbers before converting, ideally with a tax professional who knows federal benefits.

Fund Fees, the G Fund, and What TSP Cannot Offer

Federal employees have heard for years that the thrift plan has the lowest fees anywhere. That was more accurate in 2019.

Fund	Expense Ratio	Competitor	Competitor Ratio
C Fund (S&P 500)	0.036%	Fidelity FZROX	0.00%
C Fund (S&P 500)	0.036%	Fidelity FXAIX	0.015%
S Fund (Extended Market)	0.051%	Fidelity FSMAX	0.035%
I Fund (International)	0.038%	Vanguard VXUS	0.07%
G Fund (Govt Securities)	~0.037%	No equivalent	N/A

Fidelity's zero-fee index funds are now cheaper than the C Fund. On a $500K C Fund balance, the difference is about $105 per year. Real over a decade, but it does not come close to the value of the agency match.

The G Fund is a different story. Government-backed returns with no mark-to-market risk at around 0.037%. No private IRA or brokerage account has anything like it. If you leave the plan entirely, you lose that access permanently.

The other thing private accounts offer that the plan cannot is broader investment access. A Roth IRA at Fidelity or Vanguard gives you small-cap value, REITs, international small-cap, sector ETFs, individual equities. The plan's five core funds (G, F, C, S, I) cover the basics but nothing beyond that.

The Mutual Fund Window technically expands the options. For $132/year plus $28.75 per trade, you can access roughly 5,000 outside mutual funds, capped at 25% of your balance. On a $500K account, the cap is $125,000. The platform fee on that allocation is 0.106%, which wipes out most of the expense-ratio savings vs. just opening a separate IRA. Only 0.08% of TSP participants use it. Worth knowing about, but not the answer to the diversification question for most people.

Frequently Asked Questions About TSP at $500K

Should I stop contributing to TSP after I hit $500K?

No. Stopping means losing the agency match, which is an immediate 100% return on the first 3% you contribute. The focus of your strategy should shift from accumulation to tax diversification. Continue contributing, but evaluate shifting new contributions from traditional to Roth and consider starting a conversion plan for your existing balance.

What are the contribution limits for 2026?

The 2026 elective deferral limit is $24,500. If you are 50-59 or 64+, you may add $8,000 in catch-up contributions for a total of $32,500. If you are ages 60-63, the "super catch-up" allows an additional $11,250 for a total of $35,750. Employees who earned more than $145,000 in 2025 must direct their catch-up contributions to Roth in 2026.

Is TSP cheaper than Vanguard or Fidelity?

Not always. The G Fund is uniquely valuable and has no private sector equivalent. The C Fund at 0.036% is now slightly more expensive than Fidelity's zero-fee FXAIX at 0.015%. On a $500K balance, the fee difference is typically under $200 per year. The agency match value dwarfs fee differences entirely.

What is the biggest tax risk of a large traditional TSP balance?

Required minimum distributions starting at age 73, which force withdrawals regardless of need. A $1 million traditional balance at 73 requires a minimum withdrawal of roughly $37,736. That income is 100% taxable, stacks on top of your FERS pension and Social Security, and can push you into a higher bracket while triggering Medicare IRMAA surcharges.

What can a Roth IRA do that TSP cannot?

Roth IRA has no RMDs ever, while Roth balances inside the plan require distributions unless rolled to a Roth IRA after separation. Roth IRA allows targeted withdrawals from a specific account rather than proportional plan withdrawals. Roth IRA contributions can be withdrawn at any time without penalty. Roth IRA also provides access to thousands of funds beyond the plan's five core options.

Related Resources

• TSP Roth In-Plan Conversion Guide 2026: Step-by-step on the January 2026 conversion feature
• TSP Withdrawal Guide 2026: RMDs, Rule of 55, and withdrawal sequencing
• TSP Millionaire Strategy 2026: How federal employees reach $1M+ and what they do differently
• Tax Planning for Federal Retirees 2026: IRMAA, bracket management, and Roth conversion math
• Best TSP Allocation 2026: Fund allocation by age and risk tolerance
• TSP Guide 2026: Complete reference for contribution limits, fund options, and withdrawals

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Sources:

• TSP Contribution Limits -- Official 2026 limits
• TSP SECURE 2.0 Overview -- RMD age and catch-up changes
• IRS RMD FAQs -- Uniform lifetime table, calculation rules
• FedSmith: Roth In-Plan Conversion Launch -- January 28, 2026 launch confirmed
• FedSmith: TSP or IRA in Retirement? -- IRA advantages for federal employees
• FedSmith: Navigating RMDs -- RMD management strategies
• FedWeek: Roth Conversion Ladder -- Conversion ladder strategy for feds
• GovExec: TSP Diversification Reality Check -- C Fund concentration analysis
• Vanguard: Roth IRA Income Limits 2026 -- Phase-out thresholds
• Federal Pension Advisors: IRMAA Brackets 2026 -- Medicare surcharge thresholds