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What to Do With a Maxed-Out 401(k): A Guide for High Earners in Their 40s and 50s

  • Writer: Gustaf Rounick, CFPⓇ
    Gustaf Rounick, CFPⓇ
  • May 14
  • 8 min read

Savings Waterfall" showing the 6-step priority order with 2026 limits.

Let's walk through each one.

The HSA: The Best Account You Are Probably Underusing

If you are on a high-deductible health plan, the Health Savings Account is the most tax-advantaged account in the U.S. tax code. It is the only account that offers a true triple tax advantage: contributions are tax-deductible, growth is tax-free, and withdrawals for qualified medical expenses are tax-free.³

The 2026 contribution limits are $4,400 for individual coverage and $8,750 for family coverage. Those age 55 and older can add another $1,000.⁴ For a California family in a 32% federal and 9.3% state bracket, that family contribution alone may shelter over $3,600 in taxes the year it is made.

Most people use their HSA the wrong way — they spend it on current medical bills. The more powerful strategy is to pay your medical expenses out of pocket today, save every receipt, and let the HSA balance grow invested for decades. There is no time limit on self-reimbursement. You can submit a receipt from 2026 to your HSA in 2050 and pull the money out tax-free.⁵

The math gets compelling. A 35-year-old maxing the family HSA at $8,750 per year and earning 7% returns could accumulate roughly $860,000 by age 65 — fully available, tax-free, for medical expenses.⁶ And Fidelity estimates that a 65-year-old retiring today will spend approximately $172,500 on healthcare during retirement.⁷ Those numbers fit together unusually well.

After age 65, the HSA effectively becomes a traditional IRA with a bonus: non-medical withdrawals are taxed as ordinary income (no penalty), and medical withdrawals remain tax-free. The 20% early withdrawal penalty disappears at 65.

The HSA Triple Tax Advantage" diagram showing the three tax benefits and the receipt-saving strategy.

The Backdoor Roth IRA

For most high earners in their 40s and 50s, direct Roth IRA contributions are off the table. In 2026, single filers earning more than $168,000 and married couples earning more than $252,000 cannot contribute directly.⁸ That is a meaningful chunk of professionals in the Westside LA area.


The workaround is the backdoor Roth, a strategy the IRS has effectively blessed since 2010. Here is how it works:


1. Contribute up to $7,500 to a traditional IRA on a non-deductible (after-tax) basis. If you are 50 or older, that limit rises to $8,600 in 2026 — the IRA catch-up is now indexed to inflation under SECURE 2.0.²

2. Shortly after, convert that traditional IRA balance to a Roth IRA.

3. File IRS Form 8606 with your tax return to document the basis and the conversion.


There is one major trap: the pro-rata rule. If you have other pre-tax IRA balances — say, a rollover IRA from an old 401(k) — the IRS treats all of your traditional IRA money as a single pool. You cannot cherry-pick the after-tax dollars to convert. A backdoor Roth done with a $94,000 pre-tax IRA in the background can result in almost the entire conversion being taxable.⁹


The fix: roll the pre-tax IRA back into your current employer's 401(k) (if the plan accepts it) before the backdoor conversion. That removes the pre-tax IRA balance from the pro-rata calculation. For couples, both spouses can do their own backdoor Roth — that is $15,000 to $17,200 of additional Roth money per year for a married couple, every year, indefinitely.


The Mega Backdoor Roth

This is the strategy that can move the needle the most, and the one most high earners do not know about — or do not realize their employer offers.

The IRS sets the overall 401(k) plan limit at $72,000 for 2026 (not counting catch-up).² That number includes employee contributions, employer match, and a third category: after-tax (non-Roth) employee contributions. If your plan allows them.


The math works like this. Say you earn $300,000 and contribute the $24,500 employee maximum. Your employer matches $15,000. That leaves $32,500 of room under the $72,000 ceiling. If your plan allows after-tax contributions, you can put that $32,500 into the plan — and if the plan also allows in-service Roth conversions or rollovers to a Roth IRA, you can convert that after-tax money to Roth almost immediately, getting it into tax-free status for life.¹⁰


Mega Backdoor Roth: How the Math Works" showing the $72,000 limit broken down by source.

Two conditions must be met:


●Your employer plan must allow after-tax contributions beyond the $24,500 limit

●The plan must allow either in-plan Roth conversions or in-service rollovers to a Roth IRA


Many large employers offer this — Google, Microsoft, Meta, Amazon, Apple, Netflix, Salesforce, and others have well-publicized programs.¹¹ But it is far from universal. The only way to know is to check your plan documents or ask HR. The phrase to use: "Does our 401(k) plan allow after-tax contributions and in-plan Roth conversions?"

If yours does, this single move can put tens of thousands of additional dollars into Roth status every year. Over a decade, that can mean a seven-figure tax-free balance.


Taxable Brokerage: Where Strategy Beats Limits

Once you have exhausted the tax-advantaged buckets, the next stop is a taxable brokerage account. There are no contribution limits, no income limits, and no withdrawal restrictions. The trade-off is that dividends, interest, and capital gains are taxed annually.


Three strategies make taxable accounts more efficient than people assume:

Tax-loss harvesting. When a holding drops below your purchase price, sell it to lock in the loss, then immediately buy a similar-but-not-identical investment to maintain market exposure. The loss offsets capital gains elsewhere in your portfolio, or up to $3,000 of ordinary income per year, with excess losses carrying forward.¹² The wash-sale rule prohibits buying the same security within 30 days, so the replacement has to be different enough — a Vanguard S&P 500 ETF for a Schwab S&P 500 ETF, for example.


Direct indexing. Instead of buying an index ETF, you hold the underlying stocks individually. Even in up years, individual stocks within the index move differently — some go down. That gives you many more tax-loss harvesting opportunities. Schwab estimates this can add roughly 1 percentage point of after-tax return per year over a traditional index ETF, which compounds significantly over decades.¹³ Direct indexing typically makes sense for accounts of $250,000 or more.


Asset location. Put your tax-inefficient holdings (bonds, REITs, actively managed funds) in your tax-deferred 401(k) and IRA accounts. Put your tax-efficient holdings (broad-market index funds, municipal bonds) in your taxable account. Put your highest-growth assets (small caps, international, high-conviction picks) in your Roth, where the growth is tax-free forever. The same overall portfolio can produce meaningfully different after-tax returns depending on where each asset sits.¹⁴

One more advantage of taxable accounts that often gets overlooked: the step-up in basis at death. If you hold appreciated assets your entire life, your heirs inherit them at the market value on your date of death — not your original cost basis. Decades of capital gains can effectively disappear for tax purposes.¹⁵ This is why taxable brokerage accounts often play a key role in estate planning.


529 Plans: Now Better Than Ever

If you have children or grandchildren, a 529 college savings plan offers tax-deferred growth and tax-free withdrawals for qualified education expenses. California does not offer a state tax deduction for contributions (unlike most states), but the federal benefits still apply.¹⁶

The bigger reason to consider a 529 in 2026: under SECURE 2.0, unused 529 funds can now be rolled into the beneficiary's Roth IRA, tax-free.¹⁷ The rules are specific:


●Up to $35,000 per beneficiary, lifetime

●Annual rollover capped at the Roth IRA contribution limit ($7,500 in 2026)

●The 529 must have been open for at least 15 years for that beneficiary

●Only contributions made more than 5 years ago are eligible

●The beneficiary must have earned income


This effectively eliminates the old fear of "overfunding" a 529. Even if your child does not use all of it for school, the leftover money can become Roth IRA seed capital for them — a head start on tax-free retirement savings.

The 15-year clock is the key planning point. Open the 529 as early as possible, even if you are unsure whether your child will go to college. The clock starts running the day the account is opened.


Deferred Compensation: Powerful but Risky

For executives and senior employees at large companies, a nonqualified deferred compensation (NQDC) plan can let you defer a substantial portion of salary or bonus to a future year — often retirement, when you may be in a lower bracket. There are no IRS contribution limits.¹⁸

The catch: NQDC dollars remain on your employer's balance sheet. They are not held in trust for you. If your employer goes bankrupt, you become an unsecured creditor and may receive pennies on the dollar.¹⁹ This is not theoretical — it happened to executives at GM, Lehman Brothers, and others during the 2008-2009 financial crisis.

The general rule of thumb: only defer through an NQDC plan if you trust your employer's long-term financial health, and only defer amounts you could afford to lose. Diversify across years and distribution timing. For most high earners, deferred comp is a complement to the other accounts above — not a replacement.


A California Footnote

For Los Angeles-area professionals, every one of these strategies is worth more than it would be elsewhere. California's top marginal income tax rate is 13.3%, the highest in the country, and the state taxes capital gains as ordinary income — there is no preferential long-term rate at the state level.²⁰ A high-earning California family in the 32% federal bracket and 9.3% state bracket is looking at combined marginal rates above 40% on every dollar of ordinary income.


That means every pre-tax 401(k) dollar, every HSA contribution, and every Roth conversion done in a lower-income year is saving more than it would for someone in a no-income-tax state. The flip side is that the cost of living is roughly 43% above the national average, and a $1.5 million nest egg lasts noticeably less time in California than in most other states.²¹ The numbers cut both ways.


The Bottom Line

Maxing out a 401(k) is a great milestone. It is also a starting point. The combination of an HSA, backdoor Roth, mega backdoor Roth, strategic taxable brokerage, 529s, and selective use of deferred compensation can add tens of thousands — sometimes more — to your annual tax-advantaged savings.


The right mix depends on your specific situation: your employer's plan features, your state of residence, your family structure, and your goals for retirement and legacy. No two waterfalls look exactly alike.


If you would like to walk through which of these strategies belong in your plan — and in what order — Westlight Wealth offers a complimentary introductory consultation for high earners in the Los Angeles area.


Sources

2. IRS — 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 — https://www.irs.gov/newsroom/401k-limit-increases-to-24500-for-2026-ira-limit-increases-to-7500

3. Instead — Health Savings Accounts: Triple Tax Advantage Explained — https://www.instead.com/resources/blog/health-savings-accounts-triple-tax-advantage-explained

11. Carry — Companies With Mega Backdoor Roth IRA — https://carry.com/learn/companies-with-mega-backdoor-roth-ira

13. Schwab — Direct Indexing as a Tax Strategy — https://www.schwab.com/learn/story/how-to-use-direct-indexing-as-tax-strategy

14. Schwab — How Asset Location Can Help Save on Taxes — https://www.schwab.com/learn/story/how-asset-location-can-help-save-on-taxes

15. Curchin CPA — Comprehensive Guide on the Step-Up in Basis Rule — https://www.curchin.com/curchin-blog/comprehensive-guide-on-the-step-up-in-basis-rule/

18. Voya — Pros and Cons of Nonqualified Deferred Compensation — https://www.voya.com/voya-insights/pros-and-cons-nonqualified-deferred-compensation

19. SK Wealth — Nonqualified Deferred Compensation Plan Risks — https://skwealth.com/blog/nonqualified-deferred-compensation-plans/

20. KDA Inc. — California 2026 Tax Brackets, Married Filing Jointly — https://kdainc.com/california-2026-tax-brackets-married-filing-jointly-complete-planning-guide/

21. SoFi — California Retirement Guide 2026 — https://www.sofi.com/retirement-guides-by-state/california/


Disclaimer

This article is for educational and informational purposes only and should not be considered personalized financial, tax, or investment advice. Westlight Wealth is a registered investment advisor. Registration does not imply a certain level of skill or training. Past performance is not indicative of future results. All investing involves risk, including the potential loss of principal. Tax laws are complex and subject to change; the information here reflects rules in effect as of the date of publication. Please consult with a qualified tax professional or financial advisor before making decisions about retirement savings or any other financial strategy specific to your situation.

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