Asset Location: Roth vs Traditional for Equity-Heavy Savers

Asset allocation is the what, how much in stocks, bonds, alternatives. Asset location is the where, which of those assets sit in Roth, traditional, and taxable accounts. For a senior IC with significant RSU concentration and three or four different account types, getting the location right can add 30-50 basis points of after-tax return per year, compounding to roughly 15-20% more wealth over a 30-year horizon.

The core intuition is that the tax treatment of each account differs, and the tax efficiency of each asset class differs. Match them carefully and you pay less tax over a lifetime.

This is especially true for equity-heavy earners, because the taxable account is often dominated by concentrated employer stock that can’t easily be moved or sold without a big tax bill. That constraint cascades through the other accounts.

The three account types and their tax mechanics

Traditional 401(k) and IRA (pre-tax). Contributions deduct today, grow tax-deferred, withdrawals taxed as ordinary income. Best for assets that throw off ordinary income (bonds, REITs) or that you expect to grow a lot but don’t want ordinary-income tax on the sale. Because all distributions are ordinary income, the benefit of long-term capital gains disappears inside this account.

Roth 401(k) and IRA. After-tax contributions, tax-free growth, tax-free withdrawals after 59½ and the five-year clock. Best for assets with highest expected growth, because the entire future growth is tax-free. For a 30-year-old with a 30-year runway, Roth dollars should be the highest-return assets you own.

Taxable brokerage. After-tax contributions, taxed each year on dividends and interest, capital gains on sale. Best for tax-efficient assets: broad-market index funds, municipal bonds, tax-loss-harvestable direct-indexing portfolios, and, by necessity, concentrated RSU holdings.

The standard asset-location rules

The textbook rules, adapted for an equity-heavy saver:

1. Bonds in pre-tax accounts. Interest is ordinary income, and pre-tax accounts tax everything as ordinary income on withdrawal. No loss from moving bonds there.
2. High-growth stocks in Roth. You want tax-free compounding on the assets with the highest expected return.
3. Broad-market index equity in taxable. Low turnover means low annual tax drag; qualified dividends taxed at preferential rates.
4. REITs, high-yield, and taxable bond funds never in taxable. The annual ordinary-income drag is brutal.

How concentrated RSU wrecks the textbook

Most asset-location writeups assume you can freely allocate across account types. Real senior ICs can’t. If you have $1.2M in employer stock sitting in your taxable account, half of your net worth, that stock isn’t moving. You can’t sell without capital gains tax. You can’t donate more than 30% of AGI in a single year under IRC §170(b)(1)(C)(ii). You can hedge it, collar it, or exchange-fund it, but the dollars stay in taxable.

This forces a rethink of what goes in the other accounts:

• The concentrated stock is already equity exposure. Your 401(k) and IRA should tilt toward diversifying assets: international equity, small-cap, bonds.
• Roth dollars should still hold growth, but “growth” means non-employer growth, broad-market indexes or international funds rather than more tech.
• Traditional/pre-tax can hold bonds and REITs, but if your total bond allocation is only 10% of net worth, you may not have enough pre-tax room to absorb all the bonds.

The tax-loss harvesting layer

Direct indexing in a taxable account creates a stream of realized losses that offset RSU gains at sale. A direct-indexed S&P 500 replica might harvest $8,000-$20,000 of losses per $1M per year, depending on market volatility. Those losses can be carried forward indefinitely under IRC §1212.

For an RSU-heavy employee planning to sell into a concentration over 5-10 years, tax-loss harvesting in taxable provides a “tax alpha” that shifts where you want your equity exposure. More direct indexing in taxable. Less equity in Roth (since Roth doesn’t benefit from loss harvesting).

The Roth conversion wrinkle

Asset location interacts with Roth conversions. If your pre-tax IRA holds bonds yielding 5% and your Roth IRA holds tech stocks returning 10%, a Roth conversion shifts the high-growth assets into the tax-free bucket. Converting in a low-income year (pre-IPO, sabbatical, between jobs) locks in low conversion tax and accelerates the Roth compounding.

One sequence that works for equity-heavy earners:

1. Fill Roth through mega-backdoor every year at peak earning
2. In a low-income year (sabbatical, retirement year before SS claim), convert pre-tax IRA slices up to the top of the 22% or 24% bracket
3. Reinvest Roth dollars into highest-growth assets
4. Keep pre-tax dollars in bonds so future conversions convert smaller dollar amounts

IRMAA and Medicare drag on traditional

Traditional IRA distributions count toward MAGI, which determines Medicare Part B and Part D IRMAA tiers. For 2025, the top IRMAA tier starts at $500,000 for individuals and $750,000 for couples. A large traditional IRA forces RMDs starting at 73 (or 75 under SECURE 2.0 depending on birth year), and those RMDs can push retirees into higher IRMAA brackets for decades.

This is a case for tilting toward Roth early: Roth distributions don’t count toward MAGI for IRMAA. A large Roth balance at retirement reduces forced income and keeps IRMAA tiers low.

Annual rebalancing across accounts

Rebalancing doesn’t have to happen within each account. If equities run hot in a given year, you can rebalance by selling equities in pre-tax (no tax cost) and buying bonds in pre-tax. The taxable account stays untouched. Over time, the asset allocation drifts only in the accounts you choose to move, which protects the tax lots in taxable.

For RSU-heavy earners, this means the taxable account’s equity concentration grows over time unless you actively sell. The pre-tax and Roth accounts take on more and more of the bond allocation as offset.

Frequently asked

How much does asset location actually matter? Academic estimates put the benefit at 15-25 basis points per year on average, but for high earners with tax rates above 40%, the benefit can reach 50 basis points. Over 30 years at 7% growth, that’s 15% more terminal wealth.

If I only have a 401(k) and a taxable account, is asset location still relevant? Yes. Bonds and REITs go in the 401(k); low-turnover index equity and muni bonds go in taxable. Concentrated RSU grants already occupy taxable, so the 401(k) balances the rest.

Should I put my RSUs inside a Roth IRA? Only if you’re rolling over a separated 401(k) that held them. You can’t direct-contribute employer stock into an IRA. For current grants, the stock lands in a taxable brokerage account automatically after vest.

What’s the interaction with state taxes if I move to no-tax state before withdrawal? Traditional 401(k) and IRA distributions are taxed in the state of residence at distribution, not the state where contributions happened. Roth distributions are never state-taxed. A retiree moving from California to Nevada effectively locks in zero state tax on the pre-tax balance, which shifts the Roth-vs-traditional math slightly toward traditional in accumulation.

Does the mega-backdoor Roth change asset location math? Yes, it creates more Roth capacity per year, which means you can park more high-growth assets in Roth and less in taxable. Over 10 years of mega-backdoor contributions, you might build $400,000+ in Roth. That’s room for your highest-return allocation.