The Estate-Planning Mistake That Actually Destroys Families Isn't What You Think

The most common estate-planning advice goes something like this: don't let a single stock represent too much of your portfolio. Diversify. Spread your eggs. Anyone who concentrates wealth in one company is courting disaster.

I don't think that's the real danger. Anyone with decades of experience in a company, deep conviction in its competitive position, and an understanding of its risks can hold a concentrated position rationally. The mistake that actually destroys families is more specific: believing the step-up in basis - the rule that resets an inherited asset's cost to its date-of-death value, wiping out lifetime capital gains - is a substitute for an estate plan.

It's not. It's a single provision in a much larger system, and treating it like a safety net is how families find themselves owed cash to the IRS, unable to sell core assets, or looking at trust structures that quietly eliminate the very benefit they were trying to preserve.

Here's what you need to understand.

The Step-Up Is Seductive But Fragile

When you inherit stock, your tax basis - the number the IRS uses to calculate capital gains when you sell - is reset to whatever that stock was worth on the date of death. If your parent bought shares for $5 a share thirty years ago and they're worth $150 at the time of their passing, your heirs inherit those shares at a $150 basis. The entire $145 of appreciation is never taxed at the federal level.

This is a powerful provision. And because of recent legislation, it now matters to more investors than it did two years ago. Under the One Big Beautiful Bill Act, the federal estate and gift tax exemption was set at $15 million per person - $30 million per married couple with portability - and made permanent with annual inflation adjustments starting in 2027. That means the vast majority of investors will never owe federal estate tax, and the step-up in basis applies to their heirs without triggering an estate tax return.

The seductive conclusion is obvious: why sell now, realize a capital gains tax, and give the government its share when you can just hold, die, and pass everything to your heirs tax-free? For executives sitting on $2 million to $10 million of appreciated employer stock, that argument has genuine mathematical force.

But it requires three things to go right simultaneously. Your estate has to stay under the exemption threshold. The stock has to hold or grow its value until death. And your heirs need to be able to sell after they inherit without running into liquidity or structural problems.

Any one of those failing doesn't just reduce the benefit. It can flip the entire strategy on its head.

Mistake Number 1: Trusts That Were Built for the Old Regime Are Now Working Against You

If you built an irrevocable trust - whether a GRAT, a SLAT, or an ILIT - to move appreciated stock out of your taxable estate, you may now be giving away the step-up in basis with no estate tax benefit to show for it.

Assets in an irrevocable trust are out of your estate. That was the point when the exemption was $13.99 million and everyone feared a sunset back to roughly $7 million. Now that the exemption is $15 million and permanent, most of those estates are comfortably under the threshold. But the stock inside that trust still doesn't get a step-up. Your heirs inherit it with the original cost basis from when the trust was funded, and they'll owe capital gains tax on all appreciation from that date forward.

The trade-off that made those structures sensible has flipped. For executives in the $2 million to $10 million range, I don't think estate tax was ever the real reason to hold. The real reason is conviction in the company. But if your conviction is sitting in a trust that denies its own heirs the step-up, that conviction has a hidden cost.

Mistake Number 2: Federal Estate Tax Is Off the Table, but State Estate Tax Is Not

The $15 million federal exemption is real, but it doesn't apply in twelve states and the District of Columbia that impose their own estate taxes. Connecticut, Hawaii, Illinois, Maine, Maryland, Massachusetts, Minnesota, New York, Oregon, Rhode Island, Vermont, and Washington all have estate tax thresholds far below the federal level.

New York provides a particularly brutal illustration. The state threshold is $7.16 million. An estate of $7.16 million pays zero in state estate tax. An estate of $7.2 million - just $40,000 more - triggers $108,291 in state tax. That's the cliff effect: a tiny amount of assets above the credit line wipes out the entire credit, and the estate owes on the full value.

If you live in one of these states and your estate is concentrated in a single position, the federal exemption is irrelevant. The state will look at that concentration, and the liquidity problem remains the same. You need cash to pay the tax. The asset is illiquid in a practical sense, even if the shares technically trade on an exchange.

Mistake Number 3: The Illiquidity Gap

Even when you're under every exemption and have no estate tax to pay, the date-of-death liquidity problem doesn't disappear. It shifts from a tax problem to a family-dynamics problem.

The IRS gives estates nine months to settle tax obligations. If at least 35% of the estate consists of illiquid assets, Section 6166 of the Internal Revenue Code allows deferral of payment for five years after that initial due date, with the option to pay in installments over ten more years. That's meaningful relief for a family business or a private holding, but it requires the estate to qualify and it still demands that interest be paid on the deferred balance.

For concentrated positions in publicly traded stock, the illiquidity is subtler. The shares are technically liquid. You can sell them. But if that one position represents 60% or 70% of everything you own and your heirs inherit it alongside a mortgage, living expenses, and other liabilities, the pressure to sell immediately is real. And selling immediately means selling into whatever market conditions exist at that moment - not the conditions you'd choose if you had years to plan an exit.

That gap between technical liquidity and practical liquidity is where estate plans fail. The family doesn't face an IRS bill. They face a life transition - grief, a change in income, competing priorities among heirs - and a large block of stock that suddenly needs to become rent money and healthcare costs.

What the 2026 Changes Actually Mean

The permanent $15 million exemption eliminates the urgency that drove estate-planning activity for the past three years. There's no sunset to rush before. That's good for families who were over-planning and bad for families who thought the exemption increase meant they were "done."

Income taxes, not estate taxes, are now the dominant variable. The step-up in basis is the single most valuable provision in the tax code for investors with appreciated positions. The long-term capital gains rate is 15% for most high-income taxpayers, or 20% at the top tier, plus a 3.8% net investment income tax. Wiping that out through the step-up saves a meaningful fraction of lifetime gains - but only if the position exists at death and the trust or gifting structure doesn't eliminate the step-up.

The annual gift tax exclusion remains $19,000 per recipient in 2026, or $38,000 for married couples. That's a useful tool for gradual wealth transfer, but it doesn't solve concentration. If your child receives $38,000 of your employer stock each year, they inherit it with your original cost basis. No step-up. That's a planning choice, not a free lunch.

The Framework That Actually Protects Families

This isn't about selling everything and diversifying into index funds. That's the lazy version of the answer, and it ignores the fact that concentration, when understood, is not inherently destructive.

The question is whether you can answer four things honestly:

One: What happens if this position drops 50% in the year before or after you need the money? Sequence-of-returns risk is the quiet killer. A concentrated position that looks fine on paper can devastate retirement income if it declines at the wrong time.

Two: Do your trust structures still serve the goal they were built for, or have they become obstacles? With the exemption at $15 million and permanent, some irrevocable trusts are now denying heirs a step-up that would have applied if the stock stayed in your estate. Review them.

Three: Are you exposed to state estate tax or the cliff effect? If you live in one of the twelve states with an estate tax, the federal exemption is background noise. Your planning has to address the state threshold.

Four: Is there a practical plan for liquidity at death, not just a theoretical one? Can your heirs actually convert what they inherit into the cash they need, or are you leaving them a balance-sheet problem disguised as an inheritance?

These aren't rhetorical questions. They're the mechanics that separate an estate plan from a wish.

The step-up in basis is a genuine benefit. I believe it makes holding appreciated positions longer than you otherwise would a rational choice - but only when the rest of the equation works. The exemption increase makes it more attractive than it was two years ago. But it doesn't replace estate planning. It changes which parts of the plan matter most.

From an income and risk/reward point of view, the goal isn't to avoid concentration. The goal is to know exactly what you're holding, what happens to it when you're gone, and whether the structures you've built are still doing the job they were designed for. That's what protects families. Not diversification for its own sake. Understanding.