Tax Math: Liquidate vs. Defer
TAX DEFERRAL MATH · SELL NOW OR REBALANCE TAX-AWARE?
Tax-aware rebalancing keeps more capital compounding — and more wealth yours to direct.
An interactive comparison of two paths for an appreciated position: sell it, pay capital-gains tax today, and reinvest what's left, or defer the gain through tax-aware rebalancing and keep the full amount working. The tool traces both paths year by year, net of all taxes, so the crossover is visible rather than asserted.
The core arithmetic — why deferral starts ahead
Selling does not just move money; it permanently removes the tax from your balance sheet, and that removed capital stops compounding. With the tool's default scenario:
- Position value: $10 million, against a cost basis of $1 million — a 10× gain.
- Embedded gain: $9 million.
- Tax if sold today at a 37.1% combined marginal rate: $3.34 million.
- Capital still invested after selling: $6.66 million.
- Capital still invested if deferred: $10 million — about 50% more capital compounding from day one.
That 50% head start is the whole mechanism. The deferred tax is not forgiven — it is still owed, and the tool carries it as a liability on the deferral path — but until it is paid, it compounds for you rather than for the Treasury.
Deferral is not avoidance — what the model still charges you
The comparison is deliberately honest about the costs of deferring, because a model that ignores them proves nothing:
- The deferred tax is tracked, not erased. Each path is shown net of all taxes if the position were liquidated in that year, so the deferral path never gets credit for a bill it has not paid.
- Tax-aware strategies cost more to run. The default assumes the tax-aware path gives up 0.75% a year in fees and drag versus 0.095% for the plain rebalanced portfolio. Deferral has to earn its keep against that gap.
- Rates may not be lower later. The default assumes the same 37.1% marginal rate at the end as today, so the result does not depend on a bet that taxes fall.
- Concentration risk is real. Deferring means staying exposed. Tax-aware rebalancing exists to reduce that exposure without triggering the full gain.
Every one of those inputs is adjustable — position size, cost basis, both marginal rates, holding period, pretax growth, alpha and expenses, and any liquidity you need to pull along the way.
The 401(k) analogy — why paying for deferral can still win
The common objection to tax-aware strategies is that they cost more than an index fund. The 401(k) analogy on the page answers it with a structure most investors already accept.
A 401(k) carries administrative and compliance costs that a taxable brokerage account does not, and its withdrawals are taxed as ordinary income rather than at capital-gains rates. It is, on paper, the more expensive and more heavily taxed wrapper. It still tends to win over long horizons — because nothing is pulled out for taxes along the way, so the full balance keeps compounding.
The default comparison assumes 25% of the taxable account's gains are realized through rebalancing each period at 37.1%, and that the 401(k) is withdrawn at 37.1%. Even an underperforming tax-deferred account can deliver better after-tax results than a taxable account that pays rebalancing and income taxes as it goes. That is the same arithmetic tax-aware rebalancing applies to an appreciated position.
What the chart shows
The growth comparison plots the ending value net of all taxes if liquidated in year N, for both paths, across the full horizon (20 years by default at 8% pretax growth). Reading it answers the questions the arithmetic alone cannot:
- How long until deferral is ahead after paying the deferred tax? The two lines cross at a specific year for your inputs, not in general.
- How large is the gap at your horizon? Shown in dollars and as a difference series.
- What happens if you need cash along the way? Partial liquidity needs can be scheduled, which is what usually moves the answer.
Deferral is not automatically correct. A short horizon, a high cost of the tax-aware strategy, or a near-term liquidity need can all put the sell-now path ahead — which is exactly why the comparison is a tool rather than a claim.
Frequently asked questions
Is it better to sell appreciated stock and diversify, or defer the gain?
It depends on your horizon, the cost of the tax-aware strategy, and whether you need cash soon. Selling permanently removes the tax from your compounding base: on a $10 million position with a $1 million basis at a 37.1% rate, $3.34 million leaves immediately, so deferring keeps roughly 50% more capital working. That head start compounds, but the deferred tax is still owed and tax-aware management costs more to run. Over a long horizon the head start usually wins; over a short one it may not.
Does tax deferral just postpone the problem?
It postpones the payment, which is the point — the unpaid tax keeps compounding for you in the meantime. It is not avoidance: the liability remains, and this tool shows both paths net of all taxes as if liquidated each year, so the deferral path never gets credit for a bill it has not settled. Deferral also creates optionality: gains can later be offset by losses, given to charity, or held to a step-up in basis at death.
Why pay higher fees for a tax-aware strategy?
For the same reason a 401(k) beats a taxable account despite its administrative costs and ordinary-income withdrawals: nothing is pulled out for taxes along the way, so the full balance compounds. The default comparison charges the tax-aware path 0.75% a year against 0.095% for the plain portfolio, and deferral still has to earn that difference back.
Does this assume tax rates will be lower in the future?
No. The default uses the same 37.1% marginal rate at the end of the horizon as at the start, so the result does not depend on rates falling. Both rates are adjustable if you want to test a different assumption.
What is tax-aware rebalancing?
Reducing concentration and managing risk without realizing the full embedded gain at once — using loss harvesting, offsetting positions, long/short structures, hedging, or borrowing against the position instead of selling it. The goal is to move toward a diversified portfolio on a schedule you control rather than paying the entire tax bill in a single year.