The tax break you can photocopy: How do I avoid capital gains tax when I sell my startup stock?

Sell startup stock, and the first $15 million of gain is federally tax-free. Not deferred, not discounted, zero.

That is the qualified small business stock rule, QSBS for short. Founders qualify almost by accident. So do many early employees.

Here's the part good lawyers whisper: the $15 million is per taxpayer, not per company. Gift shares to a trust, and the trust gets its own $15 million. This is called stacking, and it's how founding families turn one exclusion into four or five.

The Exclusion

QSBS, Section 1202 of the tax code, is Congress's reward for building small companies: hold qualifying shares long enough, and when you sell, the first $15 million of gain skips federal tax entirely.

At the top capital gains rate, that's about $3.6 million kept.

Two footnotes. Stock issued before July 4, 2025 carries the older $10 million cap. And if 10x what you paid for your shares is bigger than $15 million, you get that instead. For most people, $15 million is the number.

Do my shares even qualify?

Three questions decide everything, and all of them are about the day you got your shares, not how much they're worth now.

1. Was it a real startup? A C corporation with $75 million or less in assets when your shares were issued ($50 million before July 4, 2025, same idea). Nearly every venture-backed startup qualifies. Law firms, banks, hotels, restaurants, and farms don't, and neither do LLCs.

2. Did your shares come directly from the company? Founder stock qualifies. Exercised options qualify. Shares bought secondhand from another shareholder never qualify.

3. Have you held them long enough?

One warning for employees: holding options doesn't count. Options aren't shares yet, so nothing starts until the day you exercise. Your holding clock and the $75 million test both run from that day. Exercise after the company has grown past the limit, and your shares never qualify. One more reason exercising early matters.

How do I get more than one exclusion?

Gifted shares keep their QSBS status, and whoever receives them inherits your holding clock. A trust set up the right way counts as its own taxpayer, with its own $15 million. So does your spouse. So do your kids.

A founder heading toward a big exit gifts shares years ahead of time: some to a spouse, some to a trust for each child. Come the sale, the family holds four or five copies of the exclusion instead of one.

How do I actually set this up?

An estate attorney does the heavy lifting. Your job is five decisions.

1. Draft the right kind of trust. It must be an irrevocable non-grantor trust, one that pays its own taxes. That detail is the whole game: it's what makes the trust a separate taxpayer with its own $15 million.
2. Pick a beneficiary and a trustee. The beneficiary is who the money is for, usually a child. The trustee controls the money, and it can't be you. Founders typically name a sibling, a parent, or a professional trust company.
3. Get it a tax ID. The trust gets its own EIN and files its own return every year. Annoying, and exactly the point: the IRS now sees another taxpayer.
4. Gift the shares in. The company records the transfer, the shares get appraised, and you file a gift tax return. No tax is due yet. The IRS lets you give away about $15 million over your lifetime before gift tax starts (a separate allowance that annoyingly matches the QSBS cap). Gifting cheap shares barely dents it.
5. Wait. The gift needs air between it and any sale. Eighteen months or more.

All in, a few thousand dollars per trust. Each one can shelter $15 million. There are few trades in finance with that ratio.

What do I give up to do this?

The tax break is real because the gift is real. Once shares go into the trust, they aren't yours anymore.

• You can't take them back. The trust is irrevocable. Change your mind in five years, too bad.
• You can't control the money. The trustee does, and the trustee isn't you. You choose someone you trust, but the checkbook leaves your hands.
• You can't be the beneficiary. The money is for your kids, your spouse, your family. If the trust can pay you back, the IRS treats it as still yours and the extra $15 million disappears.
• The trust pays steep taxes on everything else. Trusts hit the top federal bracket at just $16,000 of income, so everything else the trust earns gets taxed hard.

One softener: married founders sometimes make the spouse a beneficiary, which keeps the money reachable inside the household. It takes careful drafting, but it's the closest thing to having it both ways. Just know your access runs through the marriage. Divorce, and it's gone.

So one honest test before any of this: if you weren't planning to pass money down anyway, the strategy has nothing for you.

Should I gift before or after the sale?

By now you might be thinking stacking looks less like a tax strategy and more like a gifting strategy. That's exactly what it is. The only real decision is whether you gift before the sale or after, and the tax code cares enormously about the order.

Run it on a $60 million exit where you want half to go to your kids. Gift after: you pay roughly $10.7 million in capital gains, then the $30 million cash gift blows past your lifetime exemption, and gift tax lands on top. Gift before: the same shares might be worth $200,000 on gift day. The exemption barely notices, and when the sale comes, nobody owes capital gains at all.

Same generosity. Same recipients. Opposite tax bills. Stacking isn't a loophole bolted onto gifting; it's gifting in the right order.

What would stacking save me?

Your exit, your stack:

The Fine Print

• Gift early. Gifts made once a sale is already brewing get unwound by the IRS. That's what the eighteen months is for.
• Make the trusts different. Cookie-cutter trusts with the same beneficiaries get treated as one. Different beneficiaries, different trustees, a real purpose for each.
• California doesn't play along. It taxes the full gain no matter what the federal rules say.
• Washington noticed. "Let me just warn you: We don't like stacking, OK?" That was a top Treasury official in May 2026, and rules limiting it are in the works. Nothing has changed yet, and structures set up years ahead are the ones expected to hold up.

What's your next move

Every QSBS test is graded on a date: the day your shares were issued, the day you exercised, the day you gifted. By the time an acquirer calls, the answers are already locked in.

The founders who exit with $60 million tax-free didn't out-negotiate the IRS at the finish line. They filed paperwork years earlier, when their shares were worth almost nothing.

If you hold startup equity, your QSBS clock is either running or it isn't, and finding out is free. To see exactly what your shares qualify for, let's chat.