QSBS (Qualified Small Business Stock)

A federal tax exclusion under Section 1202 of the tax code that allows founders and early employees of qualifying startups to exclude up to 100% of capital gains — potentially millions of dollars — from federal tax when they sell their stock after holding it for at least five years.

Qualified Small Business Stock (QSBS) is one of the most valuable and underutilized tax benefits available to startup employees and founders. Under Section 1202 of the Internal Revenue Code, taxpayers who acquire and hold stock in a qualifying small business corporation for more than five years can exclude up to 100% of their capital gains from federal income tax — with a cap of the greater of $10 million or 10× the taxpayer's adjusted basis in the stock. For someone who acquired stock for $100,000 and held it for five years before a company exit, the 10× multiplier means up to $1 million of gains could be excluded. For a founder who acquired stock for $0.001/share on a $1M valuation and watched the company sell for $500M, the $10 million cap is more likely to apply — but $10 million of gains excluded at federal capital gains rates represents roughly $2 million in tax savings at the 20% rate.

To qualify for QSBS treatment, both the company and the taxpayer must meet several requirements. The company must be a domestic C corporation (not an LLC, S-corp, or partnership) at the time the stock is issued and for 'substantially all' of the taxpayer's holding period. The company's aggregate gross assets must not have exceeded $50 million at the time the stock was issued and immediately after issuance (meaning the benefit is targeted at early-stage companies, not large established businesses). The company must be engaged in a 'qualified trade or business' — which excludes professional service firms (law, health, consulting, financial services), restaurants, hotels, and certain other industries, but includes technology, manufacturing, retail, and most other sectors. The taxpayer must have acquired the stock as an original issuance from the company (not on the secondary market), must be a non-corporate taxpayer (individuals, trusts, and pass-through entities can qualify; other corporations generally cannot), and must hold the stock for more than five years.

The 100% exclusion applies to stock acquired after September 27, 2010. Stock acquired between February 18, 2009 and September 27, 2010 qualifies for a 75% exclusion; stock acquired before that date (but after August 10, 1993) qualifies for a 50% exclusion. The remaining included gain is taxed at a maximum 28% rate rather than the standard capital gains rates, meaning even 50% exclusion QSBS provides a meaningful benefit. Congress has extended the 100% exclusion multiple times, and as of 2025 it remains available, though legislative changes are possible. Note that while QSBS excludes gains from federal tax, state tax treatment varies — California, Pennsylvania, and some other states do not conform to the federal exclusion and tax the full gain at the state level.

For employees, the most common QSBS-qualifying scenarios involve receiving stock through option exercises (ISO or NSO) and stock purchases. The five-year holding clock starts when the stock is actually acquired — for options, this is the exercise date, not the grant date. This means employees who wait to exercise options may need to hold for five or more years after exercising, in addition to whatever time passed since the grant. Early exercise (exercising options at or near grant, often paired with an 83(b) election) is a common strategy to start the QSBS clock running as early as possible. It is worth explicitly confirming with the company whether the stock qualifies as QSBS before exercising — companies sometimes change their corporate structure (converting from S-corp or LLC, for instance) in ways that affect QSBS eligibility, and not all startup stocks qualify even if the company appears to meet the obvious criteria.

Qualifying Requirements Checklist

C corporation: the company must be a domestic C corp at issuance and throughout most of your holding period — LLCs, S-corps, and partnerships don't qualify.
$50M asset cap: the company's gross assets must not have exceeded $50 million at issuance and immediately after — stock issued after the company crosses $50M in assets does not qualify.
Original issuance: you must acquire the stock directly from the company, not on the secondary market. Options that you exercise acquire qualifying stock; buying existing shares from another investor does not.
Qualified trade or business: most technology, software, manufacturing, and service companies qualify; excluded sectors include professional services (law, medicine, consulting, financial services), restaurants, hotels, and farming.
Five-year hold: you must hold the stock for more than five years. For options, the clock starts at exercise — not at grant.
Non-corporate holder: individual taxpayers qualify; other corporations generally do not. Pass-through entities (partnerships, S-corps) can pass QSBS treatment through to their individual partners/shareholders.

The Exclusion Limit

Per-issuer per-taxpayer cap: the exclusion is the GREATER of $10 million OR 10× your adjusted basis in the stock — calculated per company, per taxpayer.
10× basis: if you acquired $500,000 worth of QSBS stock, your exclusion cap is $5 million (10×) — which means gains up to $5 million are excluded.
$10 million floor: if 10× your basis is less than $10 million, the cap is $10 million. Most employees with low exercise prices and modest investments will use the $10 million cap.
Stacking with a spouse: because the exclusion applies per taxpayer, spouses who each hold QSBS can each exclude up to $10M — allowing households to potentially exclude $20M in gains.
Stacking across companies: QSBS applies per issuer — you can hold qualifying stock in multiple companies, each with its own exclusion limit. Early employees who hold equity in multiple startups over a career can accumulate substantial QSBS positions.
State conformity: California, Pennsylvania, Alabama, Mississippi, and New Jersey (among others) do not conform to the federal Section 1202 exclusion — state taxes apply to the full gain in these states.

Strategies to Maximize QSBS

Early exercise: exercise options at grant (or soon after) to start the five-year clock as early as possible — a company exit five years after a late exercise might miss the window entirely.
83(b) election: pair early exercise with an 83(b) election to establish a low cost basis and start both the QSBS holding period and the capital gains clock simultaneously.
Confirm eligibility before exercising: ask the company or its counsel whether the stock is QSBS-qualifying before exercising — not all startups qualify, and the answer depends on facts that aren't always obvious.
Hold through the five-year mark if possible: even in a tender offer scenario, if you're within 6-12 months of the five-year anniversary, the tax benefit of waiting may dwarf the tender offer opportunity cost.
QSBS rollover (Section 1045): if you must sell QSBS before the five-year hold, Section 1045 allows you to roll the proceeds into new QSBS within 60 days and inherit the original holding period — potentially deferring gains.
Consult a tax advisor: QSBS planning is highly fact-specific; mistakes in the holding period, entity type, or asset cap determination can cost millions.

Example

A software engineer joins a Series A startup in 2019 and early-exercises 500,000 ISOs at $0.05/share, paying $25,000, and files a timely 83(b) election. The company is a C corporation with $12M in gross assets at issuance — well under $50M. In 2025, more than five years after exercise, the company is acquired for $15/share. Her 500,000 shares are worth $7.5M. Her gain is $7.5M minus $25,000 = $7,475,000. Her QSBS exclusion cap is the greater of $10M or 10× $25,000 ($250,000). The $10M cap applies. She excludes the full $7,475,000 gain from federal tax — saving approximately $1.5M in federal capital gains taxes she would otherwise owe at the 20% rate. Her state is Texas, which has no income tax, so she pays zero tax on the $7.5M payout. This outcome was possible only because she exercised early, filed the 83(b), and confirmed QSBS eligibility at the time.