A founder who sells $10 million worth of startup shares may owe nothing in federal income tax on the profit, as long as the stock qualifies under the qualified small business stock rules found in Section 1202 of the tax code.
The provision has taken on new significance after recent legislation reshaped its limits, and as private fundraising stays active. According to an analysis by 24/7 Wall St., the date a founder acquired the shares can now determine whether a gain is fully sheltered or partly taxed at 28%.
Private Fundraising Keeps the Stakes High
The issue is relevant because a large volume of startup equity is being created. SEC Form D filings show 5,137 operating-company offerings raised roughly $176.3 billion in the third quarter of 2026.
Any of the shares issued in those rounds could potentially qualify for the exclusion. That only happens, however, if both the issuing company and the stock itself satisfy every requirement in the statute.
A New Cutoff Date Splits the Rules
The Working Families Tax Cuts law, Public Law 119-21, established an applicable date of July 4, 2025. Whether shares were acquired before or after that day now shapes how much gain can be excluded.
For stock acquired on or before the applicable date, the per-company dollar limit is $10 million. For stock acquired afterward, the limit rises to $15 million, and that figure will be indexed for inflation for taxable years beginning after 2026.
Any qualifying gain that is not excluded is treated as 28% rate gain, according to IRS Publication 550.
How the Caps Are Calculated
The exclusion from any single issuer is capped at the greater of the applicable dollar limit or 10 times the investor's adjusted basis in the shares of that company sold during the year. Both dollar limits are reduced by gains excluded in prior years.
There is also a trap tied to the inflation-indexed cap. Once a taxpayer's gain exceeds the limit, the limit for all subsequent years falls to zero, so founders planning multiple sales need to sequence them carefully.
A Hypothetical Founder Shows the Difference
Consider a cofounder of a software C corporation who paid $50,000 in cash for founder shares at issuance in 2018 and sells the entire stake for $10 million in 2026. The roughly $9.95 million gain sits within the $10 million cap that applies to older stock.
If that same founder had acquired the shares after July 4, 2025 and sold after three years, only $4,975,000 would be excluded. The remaining $4,975,000 would be taxed at the 28% rate. The alternative minimum tax preference in Section 57 applies only to stock acquired on or before the 2010 Small Business Jobs Act.
Questions to Answer Before Counting on the Break
Founders are advised to confirm several points: whether the company was a C corporation when shares were issued, whether the stock was original issue, whether an 83(b) election was filed, and which acquisition date applies.
Company records should also demonstrate that the business met the asset and active-business tests. For those who must sell early, Section 1045 allows gain on QSBS held more than six months to be deferred if replacement QSBS is purchased within 60 days.
What It Means for Founders and Early Employees
The exclusion is not a fit for everyone. It works poorly for founders of excluded service businesses, holders of post-2025 stock who need liquidity within three years, companies likely to exceed the asset ceiling before key share issuances, and founders who would benefit more from pass-through losses.
For those who do qualify, paperwork and timing can be worth millions of dollars. The next figure to watch is the IRS's inflation-adjusted dollar limit for 2027, which will be set through Revenue Procedure guidance.
Source: 24/7 Wall St.
