A grandparent opens a brokerage account for a grandchild, drops in some long-held stock, and feels good about it for the rest of the afternoon. That’s usually where the story stops, at least in the version people tell themselves. What actually happens next, once dividends start showing up and the account eventually gets sold, is a different story entirely. For families with real money behind these gifts, it’s worth telling that second story before the first one happens.

The short version: the IRS has a rule nicknamed the kiddie tax, and it exists specifically to stop parents from parking investment income in a child’s name to dodge a higher tax bracket. Combine that with how cost basis works when you gift appreciated assets, and a well-meant transfer can end up costing more than if you’d just left the asset where it was.

If you’re already working with an estate planning advisor, this is worth raising before any transfer happens, not after.

What the Kiddie Tax Actually Is

It’s not really a separate tax, despite the name. It’s a calculation the IRS applies to a child’s unearned income, meaning money that comes from investments rather than a paycheck. Interest, dividends, capital gains, that sort of thing. If a child has a custodial account funded with gifted stock, whatever that stock throws off in a given year falls under this rule.

Congress put it in place back in 1986. The logic was simple: without it, wealthy parents could shift investment income onto their kids’ returns and pay a fraction of what they’d owe on their own. Almost forty years later, it still does exactly that job.

The 2026 Thresholds

These numbers get adjusted for inflation, though nothing changed between 2025 and 2026.

Take a grandchild sitting on $8,000 in dividends and capital gains from a gifted account. About $5,300 of that gets taxed at the parent’s rate, not the child’s. If the parents are in a high bracket, that’s not a rounding error. And it adds up fast once you’re gifting to more than one grandchild.

Who This Actually Applies To

A child falls under the kiddie tax when all of these are true:

• More than $2,700 of unearned income for the year
• Under 18 at year end, or 18 with earned income under half their own support, or a full-time student age 19 to 23 in that same situation
• At least one parent still living
• Not filing a joint return

Wages from an actual job never count toward this. Only the investment-type income does, which happens to be exactly what appreciated stock and dividend-paying holdings tend to produce.

Where Appreciated Stock Makes This Worse

There are two problems here, not one, and most people only think about the first.

Problem One: The Ongoing Income

Once the asset sits in the child’s name, anything it earns above $2,700 a year gets taxed at the parent’s rate. If it’s a concentrated position that pays real dividends, this happens quickly, sometimes in the first year.

Problem Two: What Happens at the Sale

This is the part that catches families off guard, and it’s arguably the bigger deal for anyone gifting something that’s appreciated a lot. Gift an asset during your lifetime, and the recipient inherits your original cost basis, not what it’s worth today. That’s called carryover basis. Sell it later, and they owe capital gains on the entire run-up since you bought it, which for an old position could mean decades of gains coming due at once.

Hold that same asset until death instead, and it typically gets a step-up in basis to fair market value. The built-in gain effectively disappears for tax purposes.

Which is why that stock you’ve held since the ’90s might be the worst possible thing to gift right now, even though handing it over feels like the generous move. It’s a common blind spot, and it’s exactly the kind of thing an estate planning review catches before it becomes irreversible.

Did you know? The IRS confirmed the 2026 annual gift tax exclusion at $19,000 per recipient, unchanged from 2025, while the lifetime gift and estate tax exemption rose to $15 million per individual.

What Families Actually Do About It

None of this works well as a one-off decision. It needs to sit inside the bigger plan.

• Keep an eye on the threshold. Try to hold each child’s unearned income under $2,700, especially if there are multiple custodial accounts spread across the family.
• Lean on 529s where it fits. Earnings inside a 529 plan skip the kiddie tax entirely, as long as the money goes toward qualified education costs.
• Think about timing. Once a child ages out of these rules, or starts earning real income of their own, the math changes considerably.
• Weigh gifting against just waiting. For a low-basis, highly appreciated asset, holding it until death for the step-up can beat gifting it now, though this depends on the size of the estate, life expectancy, and what else the family is trying to accomplish. Worth modeling out rather than guessing at.
• File it correctly. Either the child files their own return with Form 8615, or, if their gross income is under $13,500, the parents can fold it into their own return using Form 8814.

Why the Stakes Are Different for Larger Estates

The thresholds are the same no matter what your net worth looks like. What changes is how much it costs to get this wrong. A family gifting a small position deals with a manageable line item on a tax return. A family moving concentrated stock, a stake in a closely held business, or real estate across several grandchildren is looking at something that can turn into a six or seven-figure mistake from a single overlooked detail.

At that point, this stops being a question you answer once and move on from. It becomes part of a coordinated plan, one that has to weigh the kiddie tax against the annual exclusion, the lifetime exemption, basis planning, and whatever the estate structure already looks like. Alpha K2 works with ultra-high-net-worth families on exactly this kind of planning, mapping how a single gift fits into the larger picture rather than treating it as an isolated move. For households also thinking through how gifting connects to the rest of their finances, our life and finance advisory services can help tie the two together.

The Point of All This

None of this means gifting appreciated assets is a bad idea. It can shrink a taxable estate, pay for a grandchild’s education, or just teach a young adult something about investing that a classroom never will. The problem isn’t the gift itself. It’s making it without first working through the income tax, the capital gains exposure, and how the kiddie tax fits into the rest of the plan.

A short conversation with an advisor before you transfer anything almost always costs less than finding out the hard way afterward. If you’re trying to figure out where appreciated assets fit into your broader wealth transfer plan, our global advisory team can walk through it with you. Or just get in touch and we’ll take it from there.

Frequently Asked Questions

1. What counts as unearned income for the kiddie tax? Interest, dividends, capital gains, rents, royalties. Not wages, not self-employment income.

2. Does the kiddie tax touch money in a 529 plan? No. As long as withdrawals go toward qualified education expenses, 529 earnings stay outside the kiddie tax entirely.

3. When does the kiddie tax stop applying? Generally at 18, unless the child is a full-time student between 19 and 23 whose earned income is less than half of their own support. In that case, it can keep applying.

4. Is it still worth gifting stock to a child if the kiddie tax kicks in? Often, yes, particularly for smaller amounts or when the real goal is shrinking the estate rather than shifting income. For a larger, concentrated position, run the numbers with someone first.

5. What’s the real difference between carryover basis and step-up basis? Carryover basis means the recipient of a lifetime gift is stuck with your original purchase price for tax purposes. Step-up basis means an inherited asset gets revalued to fair market value as of the date of death, which can wipe out most or all of the capital gains tax on the earlier appreciation.

6. How much can I gift a grandchild in 2026 without filing a gift tax return? $19,000 per recipient, no filing required. Married couples combining exclusions can go up to $38,000.

7. Do UTMA or UGMA custodial accounts trigger the kiddie tax? Yes. Anything those accounts earn counts as unearned income and falls under the same rules.

8. Should high-net-worth families just avoid gifting appreciated stock altogether? Not necessarily, it still has a place in a lot of plans. The point is weighing the kiddie tax, the carryover basis issue, and the lifetime exemption together, instead of gifting a position just because it happens to have appreciated. That’s the analysis a wealth planning advisor exists to run.