QSBS (Section 1202) after the 2025 tax-law changes: tiered exclusions and the new caps

There is a tax break that can turn a multi-million-dollar startup exit into a federal tax bill of zero, and most people who could use it have never heard its name. It is not a loophole, not a scheme, and not aggressive. It is written into the tax code, it has been there for three decades, and the 2025 tax law just made it more generous. If you hold founder stock, a restricted stock award, or early-exercised options in a young C-corporation, Section 1202 may be the single most valuable line in your tax plan.

The 30-second answer: Qualified Small Business Stock (QSBS) under Section 1202 lets an individual exclude gain on the sale of qualifying C-corporation stock from federal tax. For stock acquired on or before July 4, 2025, the exclusion is 100% after a five-year hold, capped at the greater of $10 million or 10 times basis per company. The 2025 OBBBA changed the rules for stock acquired after July 4, 2025: a tiered exclusion of 50% at three years, 75% at four, and 100% at five; a higher $15 million per-issuer cap; and a $75 million company gross-assets ceiling. The stock must be original-issuance shares in a domestic C-corp running an active qualified trade or business. Confirm details with a QSBS-specialist CPA — the 2025 changes are still being interpreted.

This is a spoke off the tax-saving playbook, which covers the legitimate plays for people with public-company RSUs. QSBS lives at the other end of the equity spectrum: it is for founders and very early employees holding actual stock in a small, private C-corporation, not for RSUs at a mature employer. The mechanics are different, the stakes are higher, and the qualification tests are unforgiving. This guide is written for US residents filing a US return.

What QSBS actually is, and why it matters

Section 1202 of the Internal Revenue Code exists to channel capital into young companies. The deal it offers is direct: invest in a qualifying small business by holding original-issuance stock, satisfy the holding-period and company tests, and the federal government waives tax on a large slice of your eventual gain.

The numbers are not marginal. The exclusion can reach the greater of $10 million (now $15 million for newer stock) or 10 times your basis, per company, per taxpayer. For a founder whose stock cost almost nothing and is worth millions at exit, that is the difference between a clean exit and a seven-figure tax bill.

Three features make QSBS unusual among tax breaks. It is an exclusion, not a deferral — the excluded gain never comes back to be taxed later, unlike a 1031 exchange or a Qualified Opportunity Fund. It is per issuer, so a serial founder or an early employee at several startups can stack a fresh cap on each qualifying company. And the excluded portion is also generally exempt from the 3.8% Net Investment Income Tax, so the saving is measured against the full 23.8% federal long-term rate, not just 20%.

The catch is that QSBS is fragile. A single failed test — wrong entity type, stock bought on the secondary market, company too large at issuance, an excluded line of business — voids the benefit entirely. There is no partial credit for almost qualifying. That is why this guide spends as much time on the tests as on the math, and why every serious QSBS position should be reviewed by a CPA who specializes in it.

Bottom line: QSBS is a genuine, statutory exclusion that can wipe out federal tax on millions of dollars of startup gain, stackable per company and largely free of the 3.8% NIIT — but it is all-or-nothing per position, so the qualification tests decide whether you get any of it.

The 2025 changes: what OBBBA did to Section 1202

For most of QSBS's life, the rule was simple and harsh: hold qualifying stock for more than five years and exclude 100% of the gain (for stock acquired after September 27, 2010); sell even one day early and exclude nothing. The cap was the greater of $10 million or 10 times basis, and the issuing company had to have aggregate gross assets of $50 million or less at and just after issuance.

The One Big Beautiful Bill Act, enacted in 2025, rewrote three of those numbers — but only for stock acquired after July 4, 2025. Stock you already held on or before that date keeps the old rules in full. The changes:

Feature	Stock acquired on or before July 4, 2025	Stock acquired after July 4, 2025
Exclusion at 3-year hold	0%	50%
Exclusion at 4-year hold	0%	75%
Exclusion at 5-year hold	100%	100%
Per-issuer cap	Greater of $10M or 10x basis	Greater of $15M or 10x basis
Company gross-assets ceiling	$50 million	$75 million

The first change is the most consequential for behaviour. The old five-year cliff meant a founder forced to sell in year four — an acquisition, a liquidity event, a life emergency — got nothing. The new tiered ramp gives 50% at three years and 75% at four, so an early sale now keeps part of the benefit instead of all or nothing.

The cap increase to $15 million and the gross-assets ceiling increase to $75 million widen the door at both ends: more gain shelters under the flat cap, and somewhat larger startups can still issue qualifying stock. The 10-times-basis alternative survives unchanged, so a founder with meaningful basis can still exceed the flat cap.

A necessary caveat: the 2025 changes are recent, and the IRS guidance, effective-date mechanics, and several interpretive questions are still settling. Treat the figures above as the framework, not the final word, and confirm anything load-bearing with a QSBS-specialist CPA before you rely on it for a sale.

Bottom line: OBBBA kept the old 100%-at-five-years deal for stock you already held, and for stock acquired after July 4, 2025 it added a 50/75/100% ramp at three, four, and five years, raised the cap to $15 million, and lifted the gross-assets ceiling to $75 million — but the new rules are still being interpreted, so verify before you act.

Worked example. The old-rule 100% exclusion

Take a founder who acquired qualifying QSBS in 2020 — well before the July 4, 2025 line, so the old rules apply. By 2026 the stock has been held more than five years, and the founder sells for a $5,000,000 gain. Basis was nominal, so the cap is the flat $10 million, and the entire gain fits under it.

	Without QSBS	With QSBS (100% exclusion)
Long-term gain on sale	$5,000,000	$5,000,000
Gain excluded under Section 1202	$0	$5,000,000
Taxable gain	$5,000,000	$0
Federal tax at 23.8% (20% LTCG + 3.8% NIIT)	$1,190,000	$0

The entire $1,190,000 federal bill disappears because the gain is below the $10 million cap and every test was met for a five-year-plus hold. State tax may still apply — several states, notably California, do not conform to Section 1202 and tax the gain in full — so "zero federal" is not always "zero tax." But the federal exclusion alone is the difference between keeping $5 million and keeping $3.81 million.

Bottom line: A qualifying pre-July-2025 position held more than five years can take a multi-million-dollar gain to $0 of federal tax up to the cap, though non-conforming states like California may still tax it, so check your state before assuming the gain is fully sheltered.

Worked example. The new tiered rule, tier by tier

Now take a founder who acquired QSBS in late 2025 — after the July 4, 2025 line, so the tiered rules apply. The stock carries a $4,000,000 gain, and we model selling at each milestone: three years (50%), four years (75%), and five years (100%). Assume the gain sits under the cap, and use the 23.8% federal long-term rate on the taxable portion.

Sale timing	Exclusion	Excluded gain	Taxable gain	Federal tax at 23.8%
At 3 years	50%	$2,000,000	$2,000,000	$476,000
At 4 years	75%	$3,000,000	$1,000,000	$238,000
At 5 years	100%	$4,000,000	$0	$0

The ramp is real money. Selling at three years still shelters half the gain and saves $476,000 against a fully taxable sale; waiting one more year to the four-year mark saves another $238,000; reaching five years saves the final $238,000 and takes the bill to zero. Under the old cliff, every one of those early sales would have excluded nothing, so the 2025 ramp transforms what an early exit is worth.

The strategic read: if a sale is coming and you are past three years, the tier you are in determines how much waiting is worth. The jump from three to four years (50% to 75%) shelters an extra 25 points of gain; the jump from four to five (75% to 100%) shelters the last 25. Whether the wait is worth the concentration risk is the same judgement call you face on any single-stock position — never let the tax tail alone drive the decision.

Bottom line: Under the post-July-2025 ramp, selling a $4,000,000 gain at three, four, and five years produces federal tax of $476,000, $238,000, and $0 respectively, so each additional year of holding past three has a concrete, quantifiable value you can weigh against the risk of staying concentrated.

Worked example. The $15M cap versus the 10x-basis alternative

The cap is the greater of a flat dollar figure or 10 times your basis, and for founders with real basis the 10x branch often wins. Take a founder who acquired post-July-2025 QSBS with a $2,000,000 basis — perhaps through an early exercise at a meaningful strike — and sells five years later for a $30,000,000 gain (fully qualifying, 100% tier).

Cap component	Value
Flat cap (post-July-2025)	$15,000,000
10 times basis (10 × $2,000,000)	$20,000,000
Cap applied (greater of the two)	$20,000,000
Total gain	$30,000,000
Excluded gain	$20,000,000
Taxable gain (gain above the cap)	$10,000,000
Federal tax on the excess at 23.8%	$2,380,000

Because 10 times the $2 million basis ($20 million) exceeds the $15 million flat cap, the founder excludes $20 million, not $15 million. The remaining $10 million above the cap is taxed normally at 23.8%, a $2,380,000 bill — but $20 million of the gain came home free. A founder with near-zero basis would have been capped at the flat $15 million instead, so basis directly buys cap room here. This is one reason early exercise, where you pay for shares and create basis, can matter beyond just starting the clock.

Bottom line: The per-issuer cap is the greater of the flat figure or 10 times basis, so a $2 million basis lifts the cap to $20 million and shelters $20 million of a $30 million gain — basis is not just paperwork, it expands how much gain you can exclude.

The qualification tests, in plain terms

Every dollar of QSBS benefit depends on the stock passing a stack of tests. Miss any one and the exclusion is gone. The tests fall into three groups.

The entity test. The issuer must be a domestic C-corporation — not an S-corp, not a partnership, not an LLC taxed as a partnership. The stock you hold must be C-corp stock at issuance. A company that converts from an LLC to a C-corp can start issuing QSBS from the conversion forward, but the clock and the tests begin then, not earlier.

The acquisition test. You must acquire the stock at original issuance — directly from the company, for money, property, or as compensation for services — not by buying it from another shareholder on the secondary market. This is why founder stock, restricted stock awards, and early-exercised options generally qualify, while shares bought in a tender offer or secondary sale do not. Stock received in exchange for other QSBS in a qualifying reorganization can carry the status forward, but plain secondary purchases never qualify.

The company tests. At and immediately after issuance, the company's aggregate gross assets must be at or under the ceiling — $50 million for older stock, $75 million for stock acquired after July 4, 2025. And the company must use at least 80% of its assets in the active conduct of a qualified trade or business. Several fields are excluded by statute:

Likely qualifies	Excluded by statute
Software and SaaS	Health, law, engineering, accounting
Biotech and pharma	Actuarial science, consulting, athletics
Hardware and semiconductors	Performing arts, financial services, brokerage
Manufacturing and industrials	Banking, insurance, financing, investing
Most product-based startups	Farming, mining, oil and gas extraction
Consumer and e-commerce	Hotels, motels, restaurants

The pattern: businesses whose principal asset is the reputation or skill of one or more employees (the service fields) are out, along with finance, hospitality, and extraction. Operating companies that build and sell a product are generally in. The line can blur — a health-tech company selling software is different from a medical practice — which is precisely the kind of edge a QSBS-specialist CPA exists to evaluate.

Bottom line: The stock must be original-issuance shares in a domestic C-corp that stayed under the gross-assets ceiling at issuance and runs an active, non-excluded trade or business — fail any one test and the entire exclusion vanishes, so the entity type, the acquisition path, and the line of business all need confirming before you count on QSBS.

How QSBS connects to your equity type

QSBS is a question about what you hold, and the answer differs sharply by equity type. This is where the spoke meets the hub.

Founder stock issued at incorporation, when the company has almost no assets and the shares cost a fraction of a cent, is the textbook QSBS case. The clock starts at issuance, the basis is tiny, and the company is comfortably under the ceiling.

Restricted stock awards (RSAs) with an 83(b) election also start the clock at grant. Because an RSA transfers actual shares subject to vesting, filing an 83(b) within 30 days fixes your basis and begins the holding period immediately, while the company is still small — exactly the conditions QSBS wants. Our 83(b) and early-exercise guide walks through the mechanics of that election.

Early-exercised options behave the same way: exercise early, file the 83(b), and you acquire original-issuance shares with the clock running and a basis equal to your exercise cost. That basis is what later expands your QSBS cap under the 10-times-basis branch.

Standard RSUs at a large public employer do not qualify, on several grounds at once: the company is far above the gross-assets ceiling, the shares are not acquired at original issuance in the QSBS sense, and a mature public company is not the small business the rule targets. If your equity is public-company RSUs, QSBS is not your tool — the tax-saving playbook and the diversification playbook are.

Bottom line: Founder stock, RSAs with an 83(b), and early-exercised options are the QSBS-eligible paths because they put original-issuance C-corp shares in your name early, while standard public-company RSUs fail on size and acquisition, so your equity type tells you immediately whether QSBS is even in play.

Common mistakes

The benefit is large enough that the errors are expensive. The recurring ones:

• Missing the 83(b) window. An RSA or early exercise only starts the QSBS clock cleanly when the 83(b) election is filed within 30 days. There are no extensions and a late filing is void, which can both raise your tax at vest and delay your QSBS clock.
• Assuming state conformity. Section 1202 is federal. Several states do not conform — California taxes the gain in full — so a "zero federal" exit can still carry a state bill. Check your state of residence at sale.
• Selling one day early under the old cliff. For pre-July-2025 stock, the five-year line is exact. Selling at four years and 360 days excludes nothing. Confirm the acquisition date to the day.
• Redemptions that poison the stock. Certain stock redemptions by the company near your acquisition can disqualify your shares under anti-abuse rules. If the company bought back stock around when you got yours, have it reviewed.
• Trusting that the company "is a small business." Gross assets are measured at and just after issuance. A later financing that pushes the company over the ceiling does not retroactively disqualify already-issued stock, but stock issued after the company crosses the ceiling is not QSBS. Timing of issuance matters.
• Treating QSBS as automatic. Nothing tags your shares as QSBS for you. You and your CPA must document the entity type, gross assets at issuance, the business activity, and your acquisition — ideally with a QSBS attestation from the company. Gather this while the company is small and the records exist, not years later at exit.

Bottom line: Most QSBS losses come from process failures — a missed 83(b) window, an assumed state conformity, a one-day-early sale, or undocumented qualification — so the discipline of confirming and documenting each test early is what preserves a benefit worth millions.

The closing read

QSBS is one of the few tax breaks where the savings are measured in seven figures and the rule is genuinely on your side — Congress built it to reward exactly the risk that founders and early employees take. The 2025 OBBBA changes made it more generous for new stock: a tiered ramp that finally rewards a three- or four-year hold, a higher $15 million cap, and a $75 million ceiling that lets larger startups still qualify. Older stock keeps the clean 100%-at-five-years deal.

But QSBS is also unusually unforgiving. It is all-or-nothing per position, it depends on facts that exist at issuance and are hard to reconstruct later, and the 2025 rules are still being interpreted by the IRS and practitioners. The two habits that protect the benefit are early documentation — capture the entity type, gross assets, business activity, and your acquisition while the company is small — and a relationship with a CPA who specializes in QSBS rather than one who has read about it. The exclusion is too large, and too fragile, to take on faith.

If you hold founder stock, an RSA with an 83(b), or early-exercised options in a young C-corporation, the question is not whether QSBS is worth understanding. It is whether you have confirmed, in writing, that your shares qualify — before the exit, not during it.

Cross-references

• The RSU tax-saving playbook for US employees — the hub this guide spokes off, for public-company RSU holders.
• What to do with vested RSUs: the diversification playbook — where the proceeds go once you have liquidity.
• Turning RSUs into a retirement corpus — 401(k) and Roth mechanics for equity-heavy earners.
• Funding life goals with RSUs — goal-based selling for a house, a 529, and more.
• The 83(b) election for RSAs and early exercise — the filing that starts your QSBS clock.
• Donor-advised funds for equity compensation — giving appreciated shares, including QSBS, at lower tax cost.
• Tax-loss harvesting and the wash-sale rule — offsetting gains in the rest of your portfolio.
• Stock options: ISO versus NSO — how exercise and tax treatment differ across option types.
• What is an RSU? — the baseline equity type QSBS does not cover.
• The complete RSU guide for US residents (2026) — the broader US equity-compensation context.

Critical disclaimer: This guide is general information for US residents, not tax, legal, or financial advice, and it does not create a client relationship. Section 1202 is technical, the 2025 OBBBA changes are recent and still being interpreted by the IRS and practitioners, and the figures, effective dates, and tests described here may be refined. State tax treatment varies, and several states do not conform to the federal exclusion. Whether any specific shares qualify as QSBS depends on facts particular to you and your company. Before relying on QSBS for any sale or election, confirm your situation with a CPA or tax attorney who specializes in QSBS.