The $40,000 Tax Move That Comes After Your 401(k) Hits Its Limit

A 58-year-old engineer in Palo Alto, married filing jointly, earns $750,000 a year, has already stuffed $4 million into 401(k)s and IRAs, and parks another $1.2 million in a brokerage account that holds a single S&P 500 fund. The 401(k) is maxed. The mega backdoor Roth is maxed. The next tax dollar saved has to come from somewhere else, and for households at this income level it almost always comes from the taxable account.

Direct indexing is how it gets done. Instead of owning the SPDR S&P 500 ETF (NYSEARCA:SPY | SPY Price Prediction), the investor holds 150 to 250 of the underlying constituents in a separately managed account that mirrors the index within a tight tracking band. The fund wrapper goes away. Every individual lot becomes a tax asset.

Why the index can rise while a third of the names bleed

SPY is up almost 9% year to date and 26% over the past year. That headline conceals what is happening beneath it. Microsoft, the third-largest holding at 5% of the index, is down 16% YTD. JPMorgan Chase is off 6%. Bank of America has lost 9% as the 10Y-2Y spread compressed to roughly half a percent and the Fed funds upper bound settled near 4%.

Inside SPY, those losses are invisible. The fund nets them against winners like NVIDIA up 21%, Exxon Mobil up 27%, and Apple up 10%, and reports one number. The direct-indexed portfolio reports 500. The losers can be sold to the IRS while the index exposure stays intact.

The $40,000 figure, worked from the bottom up

In a normal-volatility year, 30% to 50% of S&P 500 names show losses at some point even when the index finishes flat or higher. The VIX spike to almost 31 in March 2026 is a recent example: a window that created harvestable losses across most rate-sensitive financials and a chunk of mega-cap tech, even though the index recovered.

On a $1.2 million direct-indexed sleeve, that translates to roughly $30,000 to $50,000 of harvested losses per year. Call it $40,000. Applied against long-term capital gains at the 23.8% federal rate including NIIT, and the surplus $3,000 against ordinary income at the 32% bracket, that single year is worth $9,520 to $12,800 in current-year tax. Carried out over 15 years before any step-up in basis at death, the savings compound to $140,000 to $190,000.

Where this connects to Medicare and Roth conversions

Harvested losses lower realized capital gains, which lowers modified adjusted gross income, which lowers IRMAA exposure once the household crosses 63. For a 50-year-old today, this is the mechanic that opens runway for Roth conversions in the 60-to-63 window without tripping the two-year Medicare lookback. The conversion creates ordinary income; the harvested losses cannot offset it directly, but the suppressed capital gains keep the surcharge brackets clear of the conversion stack.

What to actually do

1. Price the fee drag honestly. Direct-indexing SMAs at Fidelity, Schwab, and Wealthfront run roughly 0.25% to 0.40%, against SPY’s roughly 0.1% expense ratio. On $1.2 million, the incremental fee is $1,800 to $3,700. If the harvest yields $9,500 or more in tax savings, the math works. Below roughly $400,000 in a taxable account, it usually does not.
2. Ask whether your current brokerage account can be transitioned in kind. Several platforms will migrate appreciated ETF lots into the SMA without triggering a sale by gradually unwinding the fund and building the constituent positions around it. Liquidating SPY outright on a position with embedded gains can wipe out years of harvest value in a single tax bill.
3. Coordinate the harvest calendar with concentrated stock events. RSU vests, ISO exercises, and a planned sale of a private business all create the realized gains that harvested losses are most valuable against. Pair them in the same tax year. And track wash-sale windows around dividend ex-dates: MSFT goes ex-dividend May 21, 2026 and XOM on May 15, both within the 30-day replacement window for nearby lots.

The 401(k) is the foundation. The taxable account is where affluent households quietly add another decade of after-tax compounding, and direct indexing is the lever most of them never pull.