A 56-year-old couple filing jointly, earning $400,000 a year, recently posted a portfolio summary that looks textbook on the surface and quietly bleeds money underneath. $1.4 million sits in a traditional 401(k), $400,000 in a Roth IRA, and $1.2 million in a taxable brokerage. Every account is allocated identically: 60% bonds, 40% stocks. Clean, balanced, and costing them roughly the price of a new car every year in avoidable taxes.
The fix is called asset location, and it is the most overlooked lever in a high-earner 401(k) plan.
Why Identical Allocations Are a Tax Trap
Each account type taxes returns differently. A traditional 401(k) defers tax on everything until withdrawal, then taxes it as ordinary income. A Roth pays nothing on growth, ever. A brokerage account taxes interest at ordinary rates as it accrues, but taxes qualified dividends and long-term gains at preferential rates, and gets a step-up in basis at death.
When the same 60/40 mix sits in all three, the bonds in the brokerage are the worst offender. $720,000 in brokerage bonds yielding about 4% throws off $28,800 a year in taxable interest. At a 32% federal bracket plus 6% state, that interest costs $10,944 in tax annually, none of which would have been owed had those bonds been held inside the 401(k).
That 4% assumption reflects today’s rate environment. The 10-year Treasury yield sits around 4.5%, sitting in the 93rd percentile of the past twelve months. Bond income is meaningful again, which makes where you hold those bonds matter more than it has in years.
The Three-Account Reshuffle
The optimized layout follows one rule: match each asset to the account that taxes it most lightly.
- Bonds go in the 401(k). Interest compounds tax-deferred. The ordinary-income treatment at withdrawal is irrelevant because bond interest would have been taxed at ordinary rates anyway. The shelter is free.
- Broad equities go in the brokerage. Qualified dividends are taxed at 15% to 20%, losses can be harvested against gains, and unrealized appreciation receives a step-up in basis at death. None of those features exist inside a 401(k), where every dollar eventually comes out as ordinary income.
- Highest-growth equities go in the Roth. Small-cap, emerging markets, concentrated growth positions. Whatever has the longest runway and biggest expected return belongs in the only account where the IRS never gets another dollar.
What the Math Looks Like After
Once bonds vacate the brokerage and stocks take their place, the $1.2 million brokerage throws off roughly 1.5% in qualified dividends, or $18,000, taxed at 23.8% federal for $4,284. The bond-side savings alone are $10,944 minus $4,284, or $6,660 a year.
The bigger win comes from the equity side. Stocks that previously sat in the 401(k) were headed for ordinary-income treatment at withdrawal, likely 22% to 24% in retirement. Held in the brokerage instead, the same appreciation eventually qualifies for long-term capital gains, and any unsold position passes to heirs at a stepped-up basis. That rate arbitrage adds roughly $13,000 a year in tax efficiency, bringing the total to about $24,000 annually.
Compounded over a decade of working years before retirement, that is a six-figure swing with no change in risk, no change in expected return, and no change in the underlying holdings. Only the addresses change.
Three Moves to Make This Quarter
- Rebalance inside each account, not across them. Sell bonds inside the 401(k) and buy stocks there. Sell stocks inside the brokerage and buy bonds there. Doing the swap across accounts creates capital gains in the taxable account and undoes part of the benefit.
- Use new contributions and dividends to drift toward the target. If the brokerage holds appreciated equity positions, redirect future cash flows rather than selling. With the VIX near 18 and markets calm, this is a workable window to rebalance methodically.
- Re-check the overall 60/40 once a year. Asset location only works if the portfolio-wide risk mix stays where you want it. Track the total, not the accounts.
The couple in this scenario needed three accounts that stopped looking identical. The fund lineup was fine; the advisor was fine; only the layout was broken.
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