The QSBS exclusion under Section 1202 lets you sell qualified small business stock and pay zero federal capital gains tax on up to $10 million in profit, or 10 times your basis if that number is bigger. It is the single largest tax break available to startup founders and early employees who hold stock options. Almost nobody structures their equity to actually qualify for it, and almost nobody checks until it is too late to fix.
This is not a loophole buried in obscure code. It is written directly into the tax law, has existed since 1993, and got dramatically more generous in 2010. Yet founders routinely form the wrong entity, hold stock for the wrong amount of time, or let their company drift into a disqualifying business line. Each mistake can cost millions.
QSBS has to be stock in a domestic C corporation, issued directly to you by the company (not bought from another shareholder on a secondary market), and acquired after August 10, 1993. The company must have had gross assets under $50 million at the time the stock was issued, and it must use at least 80% of its assets in an active trade or business.
That active-business requirement eliminates a long list of industries. Section 1202(e)(3) specifically disqualifies professional services firms: law, accounting, consulting, health, financial services, and anything where the business's main asset is the reputation or skill of its employees. It also knocks out hotels, restaurants, farming, mining, and banking. Software companies, biotech, manufacturing, and most product-based startups are fine.
The C-corp requirement trips up more people than anything else on this list. If your startup is an LLC or S-corp when the stock gets issued, there is no QSBS, period. Converting to a C-corp later does not retroactively qualify stock issued before the conversion. The clock and the classification both need to be right from day one.
You have to hold QSBS for more than five years before you sell it. Sell at year four, and you get none of the exclusion, no partial credit, nothing. This single rule is why founders who leave a company early or get acquired in a quick flip often miss the benefit entirely.
The holding period starts on the date the stock is issued, not the date it vests. For stock options, that distinction matters a lot. If you exercise options and the shares vest over time, the five-year clock on each tranche starts at exercise, not at grant. People who wait to exercise until right before an acquisition often discover they have zero holding period and zero exclusion.
There is a workaround in the tax code for acquisitions: Section 1045 lets you roll gain from QSBS sold before the five-year mark into new QSBS within 60 days, preserving your holding period on the rolled amount. It is a narrow fix and requires fast action, but it has saved plenty of early-exit founders from losing the exclusion outright.
The exclusion percentage depends entirely on when the stock was acquired. This is the part most people get wrong, because they assume the current 100% rule always applied.
| Acquisition Date | Exclusion Percentage | AMT Preference Item |
|---|---|---|
| Before Feb 18, 2009 | 50% | Yes, 7% of excluded gain |
| Feb 18, 2009 to Sep 27, 2010 | 75% | Yes, 7% of excluded gain |
| After Sep 27, 2010 | 100% | No |
Stock acquired after September 27, 2010 gets the full 100% exclusion with no alternative minimum tax hit. That is the version everyone talks about, and it is genuinely one of the best tax provisions on the books. Anything acquired earlier gets a partial exclusion and a smaller AMT add-back, which still beats paying full capital gains rates but is not the headline number people quote.
The $10 million cap applies per issuer, per taxpayer. Married couples filing jointly do not automatically double it the way some assume; the cap is calculated per spouse's own stock ownership, so planning who holds what matters if you are trying to maximize the exclusion across a household.
Here is where QSBS planning gets genuinely clever. The $10 million cap is per taxpayer, and a trust counts as a separate taxpayer from the person who created it. Gift QSBS shares into a few non-grantor trusts for family members before a sale, and each trust gets its own $10 million exclusion on the same underlying company stock.
This is called stacking, and sophisticated founders use it before a known liquidity event, not after. The gifting has to happen while the stock still qualifies and well before any sale is imminent, because the IRS watches for step-transaction arguments where gifts right before a deal look like an attempt to manufacture extra exclusions. Get a tax attorney involved months in advance, not days.
Spousal lifetime access trusts (SLATs) are a common vehicle for this. Each SLAT is a separate taxpayer, each can hold gifted QSBS, and each gets its own cap. A founder with $40 million in gain might legitimately shelter all of it using three or four trusts set up two years before any acquisition talks start.
Redemptions kill QSBS more often than people realize. If the company buys back more than a small amount of its own stock around the time new stock is issued, that new stock can fail to qualify under the redemption rules in Section 1202(c)(3). Founders doing secondary sales to clean up the cap table before a priced round need to check this before, not after.
Converting SAFEs or convertible notes into stock also needs scrutiny. The holding period starts at conversion, and the instrument itself was never QSBS while it was debt or a SAFE. Founders who assume their holding period started at the SAFE's issue date are wrong, and that error alone can cost a year or two of qualifying time.
Changing the company's business line is another quiet killer. A software company that pivots into something resembling a disqualified service business, even partially, risks losing the 80% active-business test. The test applies continuously, not just at issuance, so a business-model shift years later can retroactively disqualify stock that was fine when issued.
My take: QSBS planning should start the day a C-corp is formed, not the day an acquisition offer lands. Every founder raising a priced seed round in a C-corp should ask their attorney, in writing, whether the stock being issued qualifies under Section 1202. It costs nothing to ask early and costs millions to find out late.
The QSBS exclusion is a federal tax rule under Section 1202 that lets you exclude up to 100% of capital gains on qualified small business stock from income tax, capped at $10 million or 10 times your basis. It applies only to stock in a domestic C corporation acquired directly from the company and held more than five years. The size of the exclusion depends on when the stock was originally issued.
No. QSBS only applies to stock issued by a domestic C corporation. If your company is an LLC or S-corp when shares are issued, that stock can never qualify for the exclusion, even if the company later converts to a C-corp.
You lose the exclusion entirely on that sale and the full gain gets taxed as a regular capital gain. The only exception is Section 1045, which allows you to roll the proceeds into new qualified stock within 60 days and preserve your holding period on the rolled amount.
Each spouse can have their own $10 million cap on their own qualifying stock, but the cap is not automatically doubled for a household just because they file jointly. The exclusion is tracked per taxpayer and per issuing company, so ownership structure matters for maximizing the total benefit.
Gifting QSBS into a non-grantor trust creates a separate taxpayer with its own independent $10 million exclusion cap on the same company's stock. Founders with gains well above the cap sometimes use multiple trusts, set up well before any sale, to legally multiply the total tax-free amount across a family.