BLUF: If your C corporation houses both a qualified trade or business and a non-qualified one — software plus consulting, a tech platform plus a lending arm, a products business plus services in an excluded field — your shareholders' QSBS eligibility turns on a math problem: whether at least 80% of the company's assets, by value, are used in the active conduct of the qualified business. That test must be satisfied during substantially all of each shareholder's holding period, not just at issuance. Blended companies should be running the test at every stock issuance and at least annually, and documenting the results. Nobody else is going to do it for you, and by the time anyone asks the question — at exit, or on exam — it will be too late to fix.
The rule
Section 1202(c)(2)(A) requires that, during substantially all of the taxpayer's holding period, the corporation meet the "active business requirements" of Section 1202(e). Section 1202(e)(1)(A) is the operative test: at least 80 percent (by value) of the assets of the corporation must be used in the active conduct of one or more qualified trades or businesses.
Two things about that sentence deserve emphasis.
First, it is an asset test, not a revenue test. A company with 40% of its revenue coming from an excluded consulting practice can still pass if its assets are overwhelmingly deployed in the qualified side. A company with 90% qualified revenue can still fail if its balance sheet says otherwise. Revenue mix is evidence, not the answer.
Second, it is a continuous test. The statute asks about "any period," and the shareholder-level requirement runs through substantially all of the holding period. A company that qualified cleanly at its Series A can drift out of compliance as the excluded line grows, cash accumulates, or the business mix shifts — and stock issued in later rounds is tested on its own holding period. It is entirely possible to have QSBS-qualified Series A shares and disqualified Series C shares in the same company.
What counts against you
The excluded businesses are listed in Section 1202(e)(3): services in health, law, engineering, architecture, accounting, actuarial science, performing arts, consulting, athletics, financial services, or brokerage; any business whose principal asset is the reputation or skill of one or more employees; banking, insurance, financing, leasing, or investing; farming; extraction businesses; and hotels, motels, and restaurants.
On top of the 80% test, the statute imposes hard caps that a blended business can trip independently: if more than 10% of the value of the company's assets (in excess of liabilities) consists of stock or securities of non-subsidiary corporations, the company fails — Section 1202(e)(5)(B). If more than 10% of total asset value is real property not used in the active conduct of a qualified business, the company fails — Section 1202(e)(7), which adds that owning, dealing in, or renting real estate is not the active conduct of a qualified business.
What counts for you
The statute is not all traps. Majority-owned subsidiaries are looked through — the parent is deemed to own its ratable share of the subsidiary's assets and conduct its ratable share of the subsidiary's activities (Section 1202(e)(5)(A)). Assets held as reasonably required working capital of a qualified business, or held for investment and reasonably expected to be deployed within two years to fund R&D or working capital needs, count as actively used — but once the company is more than two years old, no more than 50% of its assets can qualify through the working capital rule (Section 1202(e)(6)). Start-up and research activities count as active conduct even with zero gross income (Section 1202(e)(2)). Rights to computer software producing active business software royalties count as active assets (Section 1202(e)(8)).
How to actually run the test
There are no regulations under Section 1202(e). No prescribed valuation methodology, no guidance on allocating shared assets, no definition of "substantially all." That absence does not make the test optional — it makes contemporaneous documentation the entire defense, because the burden of proof at exam is on the taxpayer, and the exam happens years after the facts.
A workable annual process looks like this. Start with a fair-market-value balance sheet, not a GAAP or tax-basis one. The statute says "by value," and that means you must put values on assets that carry little or no basis: self-created intellectual property, customer relationships, brand, workforce in place. In most operating companies these intangibles dominate the calculation, and they are exactly the assets a book balance sheet ignores.
Then allocate every asset between the qualified and non-qualified trades or businesses. Some assets allocate cleanly — the loan book belongs to the lending arm, the product codebase belongs to the software business. Shared assets (cash, headquarters, general-purpose equipment, enterprise goodwill) require an allocation method. There is no mandated approach, so pick something defensible — relative headcount, relative revenue, relative direct costs, specific identification where possible — apply it consistently from period to period, and write down why it is reasonable.
Next, run the special rules: apply the subsidiary look-through, classify cash between the working capital safe harbor and everything else (minding the 50% cap once the company is past two years old), and check the 10% portfolio stock and 10% real estate limits separately, because those are independent disqualifiers even if the 80% test is otherwise satisfied.
Finally, compute the percentage and memorialize it — a short memo with the balance sheet, the allocation methodology, the conclusions, and the date. Repeat at every stock issuance (each round starts its own clock and its own eligibility analysis), at least annually, and whenever something material happens: an acquisition, a large financing that leaves cash undeployed, the launch or growth of a non-qualified line, a real estate purchase.
If the number is close
A company hovering near the line has options while there is still time: deploy accumulated cash into the qualified business, hold the excluded activity in a structure that doesn't contaminate the issuer, or slow the growth of the non-qualified line relative to the qualified one. Restructurings carry their own tax consequences and should not be improvised — the point is that these are choices you can only make before the balance sheet fails, which is the whole argument for testing on a schedule rather than at exit.
The stakes went up in 2025
For stock acquired after July 4, 2025, the One Big Beautiful Bill Act raised the per-issuer exclusion cap to $15 million (inflation-adjusted after 2026), raised the aggregate gross assets ceiling to $75 million, and added tiered exclusions of 50%, 75%, and 100% at three, four, and five years. More companies qualify, more gain is excludable, and shareholders can claim benefits earlier. Every one of those changes makes the cost of a silent disqualification larger — and none of them changed the active business requirement. The 80% test is the same test it has always been. The only question is whether anyone at the company is checking.
This post is general information, not legal or tax advice. The application of Section 1202 to any particular company depends on its facts.
