Most founders hear about QSBS for the first time at the worst possible moment: during exit diligence, when a lawyer asks whether the company has always been a C-corp and whether anyone tracked “aggregate gross assets” at each financing round. By then it’s too late to fix anything — Section 1202 is a structuring decision, not a tax-return line item you can claim after the fact. Here’s what it actually does, what changed in 2025, and where it quietly stops applying.
What QSBS Actually Is
Qualified Small Business Stock (QSBS) is stock in a qualifying C-corporation that, if held long enough, lets the shareholder exclude some or all of the capital gain from federal income tax when they sell it — codified in Section 1202 of the tax code. It isn’t a loophole; it’s a deliberate incentive for people to put capital and labor into early-stage companies, and it can turn a startup exit from a six- or seven-figure tax bill into a $0 federal bill on the excluded portion.
It only works if the stock was eligible from the moment it was issued. You can’t convert existing shares into QSBS after the fact, and you can’t buy QSBS on a secondary market and get the same treatment — the exclusion is tied to the original issuance to the original holder (with narrow exceptions for gifts and certain estate transfers).
The Eligibility Requirements
Four tests have to be true, and three of them have to stay true for most of the holding period, not just on day one.
| Requirement | What it means |
|---|---|
| C-corporation | Stock must be issued by a US-based C-corp. An LLC (even one taxed as a corporation) and an S-corp don’t qualify — this is the single most common disqualifier for early-stage companies that “just formed an LLC.” |
| Original issuance | You must receive the stock directly from the company — as a founder, an employee exercising options, or an investor in a qualifying round — not by purchasing it from another shareholder. |
| Gross assets test | The company’s aggregate gross assets can’t exceed $50M (stock issued before July 4, 2025) or $75M (stock issued on or after that date, indexed for inflation from 2027), measured immediately before and after the stock is issued. |
| Active business | At least 80% of the company’s assets must be used in the active conduct of a qualified trade or business — and this test has to hold for substantially all of the shareholder’s holding period, not just at issuance. |
That last test comes with a list of businesses Congress specifically excluded: health, law, engineering, architecture, accounting, actuarial science, consulting, financial services, banking, insurance, farming, mineral extraction, and hotels/restaurants, along with any business whose main asset is “the reputation or skill” of its employees. Most VC-backed software, hardware, and biotech companies clear this easily. Professional-services and finance-adjacent startups often don’t, even when they’re a C-corp with modest assets.
What Changed on July 4, 2025
The One Big Beautiful Bill Act (OBBBA) made the biggest change to Section 1202 since the 100% exclusion was introduced in 2010 — but only for stock issued on or after July 4, 2025. Stock issued before that date is still governed by the old rules.
| Stock issued before 7/4/2025 | Stock issued on/after 7/4/2025 | |
|---|---|---|
| Gross assets cap at issuance | $50M | $75M (indexed for inflation from 2027) |
| Exclusion cap | Greater of $10M or 10x basis | Greater of $15M or 10x basis (indexed from 2027) |
| Holding period for exclusion | 5 years, flat 100% — no partial credit for holding less | Tiered: 50% at 3 years, 75% at 4 years, 100% at 5 years |
The exclusion cap and the 10x-basis alternative both apply per issuer, per taxpayer — the greater of the two is what you get. For a founder with a low cost basis (most founders pay near-nothing for their initial shares), the flat dollar cap usually governs. For an investor who put in real capital, the 10x-basis test can exceed the flat cap on a large enough check.
The tiered holding period is the change most worth knowing if you’re issued stock today: a founder who has to sell early — an acquihire, a forced liquidity event, a divorce settlement — no longer loses the exclusion entirely by missing the five-year mark on stock issued after July 4, 2025. They just get half of it at year three instead of all of it at year five.
A Worked Example
Say a founder is issued stock in 2026 (post-OBBBA rules apply) with a near-zero cost basis, and the company is acquired for a price that gives the founder a $12M capital gain after holding the stock for exactly 4 years.
- Exclusion cap: greater of $15M or 10x basis — at a near-zero basis, the $15M flat cap governs.
- Holding period: 4 years → 75% exclusion under the new tiered schedule.
- Excluded gain: $12M × 75% = $9M excluded from federal tax.
- Taxable gain: $3M, taxed at the 28% Section 1202 gain rate (not ordinary long-term capital-gains rates, though for most sellers 28% is still well below their ordinary income rate).
Had the same founder held one more year to hit the 5-year mark, the full $12M would have qualified for exclusion — the difference between selling at year 4 and year 5 here is roughly $840,000 in federal tax at the top capital-gains bracket. That’s the number that makes the holding-period clock worth tracking to the day, not just the year.
Where QSBS Quietly Stops Working
California, Pennsylvania, Mississippi, and Alabama don’t conform to Section 1202. California’s non-conformity is explicit and total — California Revenue & Taxation Code §18152 states outright that Section 1202 doesn’t apply for California income tax purposes, so a founder who owes $0 federally on a QSBS sale still owes California tax on the full gain at up to 13.3%. New Jersey was in the same group but recently moved toward conformity starting in 2026, with its own limitations. This is the QSBS equivalent of running the S-Corp election math state by state instead of assuming one federal answer settles it everywhere — the exclusion is real, but where you (or the company) are domiciled changes what it’s actually worth.
Redemptions can retroactively disqualify stock. If the company buys back a meaningful amount of its own stock from other shareholders around the time you’re issued yours, it can taint your shares’ QSBS eligibility under anti-abuse rules. This is a diligence item for the company’s cap table, not something an individual shareholder can fully control — one more reason to ask directly, at issuance, whether the company is tracking QSBS eligibility formally.
AMT is not a separate concern here. For stock acquired after September 27, 2010 (which covers essentially all stock founders are being issued today), 100% of the excluded gain is also excluded from the Alternative Minimum Tax calculation — a genuine improvement over the earlier version of the statute, where AMT clawed back part of the benefit.
Common Mistakes
- Forming an LLC “for now” and planning to convert to a C-corp before an exit. The QSBS clock starts at issuance, not conversion — converting late means starting the 3–5 year holding period from scratch, on a smaller universe of newly issued shares.
- Assuming secondary-market purchases carry the same treatment as founder shares. An early employee who buys shares from a departing co-founder on a secondary sale generally does not get QSBS treatment on that specific purchase, even if the company and the original shares would otherwise qualify.
- Not tracking gross assets at each financing round. The $50M/$75M test is measured at the moment of each stock issuance, not once at incorporation — a company that raises a large round can inadvertently disqualify shares issued after it crosses the threshold, even though shares issued earlier remain fine.
- Treating the exclusion cap as company-wide. It’s per taxpayer, per issuing company — a $15M cap belongs to each individual shareholder, not to the company as a whole, which is why gifting shares into separate trusts (a real but genuinely advanced strategy, sometimes called “QSBS stacking”) can multiply the exclusion across family members. That mechanism has enough estate- and gift-tax complexity that it needs its own specialist, not a blog post — treat this paragraph as “ask a lawyer,” not as instructions.
FAQ
Does QSBS apply to stock options, or only stock I already hold?
It applies once you’ve exercised options and hold actual shares, not while you’re still holding unexercised options. The holding period clock starts at exercise, which is one reason founders and early employees who early-exercise options get a meaningfully earlier QSBS start date than those who wait until vesting to exercise.
What if my company converts from an LLC to a C-corp later?
The QSBS clock starts on the date of the C-corp stock issuance, not on when the business itself started operating. Shares issued at conversion can qualify going forward, but nothing before the conversion counts, and the gross-assets and active-business tests are measured from that issuance date.
Is the $10M/$15M cap per company or across my whole portfolio?
Per company. If you hold qualifying QSBS in three different startups, each one carries its own separate exclusion cap — the caps don’t share a single pool across everything you’ve ever been issued.
Does an S-corp election disqualify QSBS the way it would for other structures?
Yes — Section 1202 requires the issuing entity to be a C-corp at the time of issuance and, generally, for the exclusion to remain intact. A company that elects S-corp status can jeopardize QSBS status for stock issued while that election is active; this is a real reason some venture-backed companies stay on C-corp even when the LLC/S-corp tax math (see the S-Corp election guide) would otherwise favor a pass-through structure.
Can investors, not just founders and employees, get QSBS treatment?
Yes — any original purchaser of qualifying stock can claim the exclusion, including angel investors and VC funds structured to pass the benefit through to their LPs. Fund structure matters here (some funds hold stock through entities that complicate pass-through treatment), which is a diligence question worth asking before wiring a check into a round, not after.
QSBS is one of the few places in the tax code where the reward for getting the structure right early is measured in millions, and the penalty for getting it wrong is silence — nobody tells you the exclusion is gone, your accountant just calculates a bigger bill than you expected at exit. If you’re structuring a new company, forming international or non-C-corp entities “to keep it simple,” or deciding when to exercise options, this is worth a real conversation with a startup-specialized tax attorney before the next round closes, not after. For the deal-structure literacy that makes conversations like that useful instead of intimidating, Brad Feld and Jason Mendelson’s Venture Deals remains the clearest plain-English map of how founders end up holding the stock this whole exclusion depends on. For more on structuring founder finances deliberately instead of by default, see the finance section on FutureSharks.
