A startup founder sells company shares worth $5 million and pays no federal capital gains tax. Another founder sells the same amount but owes nearly $1.2 million. The difference often comes down to one powerful tax provision, Qualified Small Business Stock (QSBS).
If your stock qualifies under Section 1202 of the Internal Revenue Code, you may be able to exclude a significant portion, or even all, of your capital gains from federal tax. And with the 2025 QSBS updates, the benefits became even more attractive for founders, early employees, and investors.
This guide explains how the Qualified Small Business Stock tax exemption works, who qualifies, how much you can save, and what to know before selling your shares.
(One language note: people search for the QSBS “exemption,” but the tax code officially calls it a capital gains exclusion under Section 1202. Same benefit, different word.)
What Is Qualified Small Business Stock (QSBS)?
Qualified Small Business Stock is stock issued by an eligible U.S. C corporation that meets the requirements in Section 1202 of the Internal Revenue Code. When those requirements are met, shareholders can exclude part, or all, of the capital gain from selling the stock from federal income tax.
Congress created QSBS to encourage investment in small businesses and startups. Today it’s one of the most valuable tax planning tools available to founders and investors, used by entrepreneurs, angel investors, and early employees who receive equity.
2025 Changes to the QSBS Tax Exclusion
The One Big Beautiful Bill Act (OBBBA), signed into law on July 4, 2025, introduced the most significant QSBS updates in over a decade. These changes apply only to stock acquired after July 4, 2025. Older stock keeps the prior rules.
New holding-period tiers. The old five-year “all or nothing” cliff is gone. Now you can exclude:
- 50% of eligible gain after 3 years
- 75% after 4 years
- 100% after 5 years
Higher exclusion limit. The per-issuer cap rose from $10 million to the greater of $15 million or 10× your investment basis, with future inflation adjustments.
Larger company threshold. The gross-asset limit increased from $50 million to $75 million, letting more growing businesses qualify.
One important caveat: on the 50% and 75% tiers, the portion of gain that isn’t excluded is taxed at a 28% rate (plus the 3.8% net investment income tax if it applies), not the standard long-term capital gains rate. The full 100% exclusion at five years remains the cleanest outcome.
How Much Can You Save?
The savings can be substantial. Assume QSBS acquired after July 4, 2025, a low basis, and a $5 million gain:
| Scenario | Gain Excluded | Approx. Federal Tax |
| Stock does not qualify | $0 | ~$1,190,000 |
| QSBS held 3 years (50%) | $2,500,000 | ~$700,000 + NIIT |
| QSBS held 4 years (75%) | $3,750,000 | ~$350,000 + NIIT |
| QSBS held 5+ years (100%) | $5,000,000 | $0 |
For someone selling millions in startup stock, the difference can mean hundreds of thousands, or millions, in federal tax savings.
Eligibility Criteria for the QSBS Exclusion
Not every business or shareholder qualifies for the QSBS Section 1202 exclusion. Eligibility is tested at both the company and shareholder level, and the conditions must hold across your entire holding period.
Company-Level Requirements
- The issuer must be a U.S. C corporation (not an LLC, S corp, or partnership).
- The corporation’s gross assets must be within the allowable limit when the shares are issued ($50M for older stock, $75M after July 4, 2025).
- At least 80% of the company’s assets must be used in an active qualified trade or business.
Shareholder-Level Requirements
- You must be an individual, trust, or other non-corporate taxpayer.
- You must have acquired the stock directly from the company at original issuance, not purchased it from another shareholder.
- You must meet the applicable holding period for the exclusion tier you’re claiming.
Excluded Industries
Some businesses can never issue QSBS, including accounting, law, consulting, financial services, hospitality, performing arts, and farming. Many technology, software, manufacturing, biotech, and product-based companies generally qualify.
Additional Tax Planning Strategies
Section 1045 rollover. If you’ve held QSBS more than six months but need to sell before reaching your target holding period, a common situation in pre-IPO tax planning, Section 1045 may let you defer the gain by reinvesting the proceeds into another qualified small business within 60 days, carrying your holding period forward.
QSBS stacking. Because the exclusion cap applies per taxpayer, some families gift QSBS to spouses, family members, or non-grantor trusts (each with their own cap) to multiply the total gain eligible for exclusion. This should always be done with professional guidance.
How Capital Tax Can Help
QSBS is one of the most valuable provisions in the tax code, but also one of the most technical, and a single misstep on entity type, issuance, or timing can cost the entire exclusion. Capital Tax works with founders, early employees, and investors to confirm eligibility and capture the full benefit before a sale closes the window.
Our team can help you:
- Confirm your QSBS eligibility by reviewing your company’s structure, gross-asset history, business activity, and your acquisition dates lot by lot.
- Structure for qualification early, including C-corporation conversions and documentation that holds up under IRS scrutiny.
- Model your exclusion and exit timing across the new 3, 4, and 5-year tiers, so you know exactly what a sale costs at each point.
- Plan the AMT on ISO exercise so exercising your options doesn’t trigger an avoidable tax bill.
- Plan around state taxes and residency, which matters in non-conforming states like California where the gain can still be fully taxable.
- Apply advanced strategies such as Section 1045 rollovers and trust-based stacking to extend the benefit beyond a single exclusion cap.
The earlier you involve an advisor, the more options stay open. A short QSBS eligibility review now can protect a six or seven-figure exclusion later.
Bottom Line
The Qualified Small Business Stock tax exemption remains one of the most valuable tax-saving opportunities available to founders, early employees, and investors. The 2025 updates let more businesses qualify, raised the exclusion limits, and made partial benefits available before the traditional five-year mark. But qualifying isn’t automatic, and the details matter. If you’re planning to sell startup stock or expect to receive equity, review your QSBS status early and schedule a meeting well before any sale. Proper planning today could save a substantial amount in federal capital gains tax tomorrow.
Frequently Asked Questions
What is Qualified Small Business Stock (QSBS)?
QSBS is stock in an eligible U.S. C corporation that may qualify for a federal capital gains exclusion under Section 1202. When the requirements are met and you hold the stock long enough, you can exclude much, or all, of the gain when you sell.
Who qualifies for the QSBS tax exemption?
Generally, non-corporate taxpayers, including founders, early employees, and investors, who receive stock directly from an eligible C corporation at original issuance and meet the holding period. The company must also pass the gross-asset and active-business tests, and certain service industries are excluded.
How long do I need to hold QSBS?
For stock acquired after July 4, 2025, you can exclude 50% after 3 years, 75% after 4 years, and 100% after 5 years. Stock acquired on or before that date still follows the old rule, which requires more than five years to exclude any gain.
Does California recognize the QSBS tax exclusion?
No. California does not conform to the federal QSBS rules, so a gain that is fully excluded federally may still be taxed at the state level, which makes residency and timing important to plan for.
Can LLCs or S corporations issue QSBS?
No, only an eligible domestic C corporation can issue QSBS. A business can sometimes convert to a C corporation so that future shares qualify, but the holding-period clock only starts on stock issued after the conversion.