What is QSBS, and how can it exclude tax on a big chunk of your gain?

The basic idea

QSBS is stock that meets the requirements of Section 1202. If your shares qualify and you hold them long enough, you may be able to exclude a large portion, in some cases all, of your gain when you sell, up to a cap. The point of the rule is to reward long-term investment in small, active businesses, and startup equity is the classic case.

Because the dollars involved at a successful exit can be enormous, QSBS is one of the highest-leverage planning topics for founders, and one of the easiest to accidentally disqualify.

The core requirements, in plain terms

The specific thresholds and percentages are set by statute and have been changed by legislation over the years, so the descriptions below are general. Treat the exact numbers as something to verify for the year and facts that apply to you.

• It must be C corporation stock. Interests in an LLC or S corporation generally do not qualify. The entity type at issuance matters.
• You generally must acquire it at original issuance. That means getting the stock from the company itself (for cash, property, or services), not buying it from another shareholder on the secondary market.
• The company must be small enough at issuance. There is a ceiling on the company's gross assets around the time the stock is issued. Above that size, newly issued stock does not qualify.
• The business must be an active, qualifying trade. The company has to use most of its assets in a qualified business. A number of fields, including many health, law, finance, consulting, and other service or professional businesses, are specifically excluded.
• You must meet a minimum holding period. The full benefit requires holding the stock for at least a set period. The length of that period, and whether shorter holds get a partial benefit, are among the details that have been adjusted by law.
• The exclusion is capped per issuer. There is a limit on how much gain you can exclude from any one company, and the exclusion percentage can depend on when the stock was acquired.

The July 4, 2025 dividing line

A 2025 law (the One Big Beautiful Bill Act) meaningfully expanded QSBS, but only for stock issued after July 4, 2025. Stock issued on or before that date stays under the older rules. So the first question for any QSBS analysis is now: when was the stock issued?

One nuance on the new tiers: for the 50% and 75% partial exclusions, the portion of gain that is not excluded is generally taxed at a 28% capital gains rate plus the 3.8% net investment income tax. The 100% exclusion at five years remains the headline benefit.

The core eligibility rules above (C corporation, original issuance, an active qualifying business, and a noncorporate holder) apply under both versions. The 2025 changes loosened the thresholds and softened the old five-year cliff; they did not change what counts as QSBS in the first place.

Why founders care so much

For a founder, QSBS planning starts at formation, not at exit. Choosing a C corporation, issuing founder stock cleanly at the start, and documenting qualification all happen years before there is any gain to exclude. Decisions made early, like converting an LLC, raising money in a certain structure, or how the company handles stock buybacks, can quietly help or hurt eligibility later.

There are also ways the benefit can be expanded or preserved through planning, and ways it can be accidentally lost. Getting it right is detailed work, but at exit it can be worth an extraordinary amount, which is exactly why it deserves attention long before a sale is on the horizon.

QSBS questions people ask

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