I'll just say the quiet part: tax-loss harvesting defers tax. Each loss you harvest reduces your tax bill today by adding to the eventual gain you'll recognize when you finally sell. If you sell in five years, you pay tax then. If you sell in twenty, you pay tax then.
If you never sell — if you hold the position until you die — your heirs inherit it at fair market value, not your original cost basis. Decades of deferred gains evaporate at that moment. Section 1014 of the Internal Revenue Code is the closest thing in the U.S. tax code to magic.
What §1014 actually says
From the statute (paraphrased):
"The basis of property in the hands of a person acquiring the property from a decedent... shall... be the fair market value of the property at the date of the decedent's death."
Three words to underline:
- Acquiring — the heir is the one whose basis resets, not the decedent. The decedent's tax obligations are separate (estate tax may apply, but that's a different rule).
- From a decedent — the asset has to pass through the estate. Gifts during life don't get a step-up; the recipient inherits the donor's basis (a "carryover basis").
- Fair market value at death — not what the decedent paid, not what it was worth a year ago. The closing price on the date of death (or six months later, for estates electing the alternate valuation date).
A worked example
Suppose you bought $500K of Apple stock 25 years ago. It's now worth $5M. If you sell, the long-term capital gain is $4.5M. Federal LTCG at 23.8% (20% top bracket + 3.8% NIIT) is $1.07M. State tax in California adds another ~$594K. Total tax bill on sale: about $1.66M — even after a quarter-century of careful tax-aware management.
If instead you hold through death, your heirs receive the position at $5M basis. They sell the next day for $5M. Capital gain: zero. Tax bill: zero. The same position. The same dollars in the family. A dramatically different tax outcome.
| Strategy | Sale price | Cost basis | Realized gain | Federal + CA tax |
|---|---|---|---|---|
| Sell in life | $5,000,000 | $500,000 | $4,500,000 | ~$1,664,000 |
| Heir sells at step-up | $5,000,000 | $5,000,000 | $0 | $0 |
The $1.66M difference is the dollar value of the step-up rule on this single position.
Why this changes how you think about TLH
This is the part nobody mentions in the harvest-and-rebuy brochures: the deferral isn't temporary if you don't sell. TLH lowers your tax bill this year by reducing realized gains (or offsetting ordinary income up to $3K). Each harvested loss also reduces the basis on the replacement security, which increases the unrealized gain inside the position.
Without the step-up, that increased gain just sits there waiting to be paid back when you sell. With the step-up, that gain is forgiven at death.
So the structural play for a high-bracket investor with a long horizon looks like:
- Harvest losses aggressively while alive. Capture $50K, $200K, $500K of cumulative losses. Use them to offset gains and ordinary income.
- Don't sell appreciated positions unless you have to. Use loss carryforwards to absorb any forced sales.
- Hold through death. The accumulated unrealized gain (which is now larger than it would have been without TLH, because TLH lowered basis) gets stepped up.
- Heirs receive the position at full market value with zero embedded tax liability.
What can go wrong
Three things break the plan:
1. You sell before you die
Obvious but worth stating. If you sell at any point during your life, you recognize the gain and pay the tax. The step-up only applies to property that passes through your estate.
This is why concentrated-stock decumulators often donate appreciated positions to charity instead of selling them — the charity gets the position at fair market value (no tax), and the donor takes a deduction for the full market value. The basis problem disappears in a different way.
2. You gift during life
Gifts to family during life carry over the donor's basis. Your $500K-basis Apple stock, gifted to a child, lands in the child's account at $500K basis. When they sell, they pay the same tax you would have. The step-up only applies at death.
This is occasionally a feature (gift to a low-bracket family member who then sells). More often it's a tax mistake people make without realizing.
3. The estate-tax rule changes
The step-up at death is currently the law, and has been since 1921 with various adjustments. The Tax Cuts and Jobs Act of 2017 doubled the estate-tax exemption (now ~$13.6M per person in 2026). Some proposals have argued for eliminating the step-up entirely or capping it at modest amounts. None has passed.
This is the policy risk of any long-horizon strategy: the rules might change. The constant shape across decades of changes is that direct ownership of appreciated capital assets has been treated more favorably than realizing gains in life.
The honest summary
If you're under 50 with a long earnings curve ahead and a taxable account, the combination of TLH + buy-and-hold + eventual step-up is arguably the most powerful structural advantage available to a self-directed investor. The math works out to multi-million dollar differences over 30-year horizons on seven-figure accounts.
If you're 75 with a $5M portfolio and worried about your tax situation, do not sell. The single most expensive thing you can do today is liquidate appreciated positions you don't need to spend.