Selling your startup stock and paying zero federal tax on millions in gains sounds too good to be true. For founders and early investors in small businesses, QSBS makes it real.
QSBS stands for qualified small business stock, and the rules behind it sit in Section 1202 of the tax code. When your stock qualifies and you hold it long enough, you can exclude a huge chunk of your capital gain from federal tax. It is one of the most generous tax incentives in the code, and a 2025 tax law made it even better.
This guide covers what QSBS is, the exclusion you get, who is eligible, and the new rules you need to know.
QSBS is stock in a qualified small business that gets special treatment under Section 1202 of the Internal Revenue Code.
The idea is simple. To reward people who back small businesses, the tax code lets you exclude gain when you sell qualifying stock. The company has to be a C corporation, the stock has to be acquired at original issuance, and you have to hold it for a set period. Meet the rules and a sale that would normally trigger a big capital gains bill can come out largely or completely tax-free.
That is the whole promise here: real money kept instead of paid.
The headline tax benefit is the gain exclusion, and it is large.
Under Section 1202, you can exclude the greater of $10 million of gain or 10 times your tax basis in the stock, per company. On a qualifying sale, the QSBS exclusion can wipe out your entire federal capital gains tax, and because the excluded gain is not income, it also stays out of the net investment income tax and the alternative minimum tax. The tax savings on a big exit can run into the millions. That is the kind of number that changes how founders plan a sale.
A multi-million-dollar gain, federally tax-free. That is why founders care so much.
Eligibility is where QSBS gets strict, so this is the part to read twice.
To qualify, the company must be a domestic C corporation, not an S corp or LLC, with gross assets of $50 million or less immediately after the issuance of your stock. You must acquire the shares directly from the company at original issue, in exchange for money, property, or services, rather than buying them from a shareholder. The business also has to run an active qualified trade or business, putting at least 80% of its assets to work in that trade. Miss any one of these and the stock does not qualify.
Original issuance, the right entity, active business. Those three pillars hold the whole thing up.
The catch that trips up most people is time, because you have to hold the stock long enough.
The classic rule is a five-year hold: holding QSBS for at least five years from the issue date earns the full exclusion. Sell before five years and you normally get nothing under the old rules, though you can sometimes roll the gain into another QSBS investment to keep the clock alive. This rule is why the benefit rewards patience, and why timing a sale around that five-year mark matters so much.
Five years is the magic number under the original rules. The newer rules soften it.
The 2025 law rewrote parts of the rules, and the changes are friendly to founders.
For QSBS issued after July 4, 2025, the all-or-nothing holding period turns into a tiered exclusion. Hold for three years and you exclude 50% of the gain, four years gets you 75%, and five years still gets you the full 100%. The act also raised the per-company cap from $10 million to $15 million, and lifted the gross asset limit from $50 million to $75 million, so larger startups now fit. Stock acquired before that date keeps the old rules.
Shorter timelines and bigger caps. The newer law made a good deal even better.
Not every small company can issue QSBS, no matter how it is structured.
Section 1202 rules out a long list of trades, including most professional services like law, accounting, health, and consulting, plus finance, insurance, farming, hospitality, and any business whose main asset is the reputation or skill of its employees. So a software company usually qualifies for the QSBS exclusion, while a consulting firm usually does not. The point is to steer the benefit toward small businesses that build products, not service practices.
If the business sells expertise rather than a product, the break is often out of reach.
Earning QSBS status is one thing. Keeping it is another.
A company can lose QSBS treatment by buying back too much of its own stock around that time, or by drifting out of the active business test. On your side, you keep the holding period running and document your basis and acquisition date carefully, because you will need that proof years later when you sell. Good records from day one are what protect the capital gains tax exclusion when it finally matters.
Treat it as a status you maintain, not a box you check once.
QSBS is worth millions, which is exactly why it pays to get it right.
The eligibility tests, the timing, and the new rules all reward careful work with a tax advisor. One missed detail at issuance can cost a founder the entire exclusion years later. This is the kind of high-stakes tax planning US CPA firms hand to us at Madras Accountancy, from confirming eligibility to documenting the tax position behind a claim. If a client holds startup stock, reach out.
What is QSBS? QSBS, or qualified small business stock, is stock in a qualifying C corp that gets favorable treatment under the rules. Hold it long enough and you can exclude a large share of your capital gain from federal tax under the rules.
How much gain can you exclude with QSBS? You can exclude the greater of $10 million or 10 times your basis, per company. This QSBS tax exclusion grew under a 2025 tax law that raised the $10 million figure to $15 million for stock acquired after July 4, 2025.
What are the QSBS eligibility requirements? The company must be a C corp under the gross asset cap when the stock is issued, run an active business, and you must acquire the shares at original issue. The newer rules lift that ceiling higher.
How long do you have to hold QSBS? The traditional holding period is five years for the full exclusion. For stock issued after July 4, 2025, a tiered exclusion applies: 50% at three years, 75% at four, and 100% at five.
What did the 2025 tax law change for QSBS? It added the tiered exclusion for shorter holding periods, raised the per-company cap from $10 million to $15 million, and increased the asset limit to $75 million, all for stock acquired after July 4, 2025.
Does an LLC or S corp qualify for QSBS? No. Only stock in a domestic C corporation can be QSBS. An LLC or S corp would need to convert to a C corp first, and the clock starts from the date the qualifying stock is issued.
Which businesses do not qualify for QSBS? Service businesses such as law, health, accounting, consulting, and financial services, along with farming, hospitality, and natural resource companies, are excluded. The benefit is aimed at product and technology businesses.
Do you pay any tax on a QSBS sale? If your gain is fully excluded, you owe no federal capital gains tax and no investment surtax on the excluded amount. State tax treatment varies, since not every state follows the federal exclusion, so check your state rules.
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