Section 1045 QSBS Rollover: Defer Gain Into New Qualified Stock
If you sold QSBS before the five-year mark, Section 1045 lets you defer capital gain by reinvesting the proceeds into new qualified small business stock within 60 days. The window is short, the replacement stock requirements are strict, and California will still tax you — but for serial founders and active angel investors, the math is often worth the effort.
§1045 versus §1202: defer versus exclude
These two provisions work together but serve different purposes. Understanding which one applies — and when — is the first step in any rollover analysis.
| Feature | §1202 Exclusion | §1045 Rollover |
|---|---|---|
| What it does | Permanently excludes gain from federal tax | Defers gain into replacement stock; tax is not forgiven |
| Minimum holding period | 5 years (or shorter tiered period under OBBBA for post-July 4, 2025 stock1) | More than 6 months |
| What triggers the benefit | Sale at or after minimum holding period | Sale before minimum §1202 period, with reinvestment in new QSBS within 60 days |
| State tax | Not available in CA, PA, AL, MS and other non-conforming states | Not available in CA, PA, AL, MS and other non-conforming states |
| End result if replacement stock also qualifies | — | Deferred gain may ultimately be excluded under §1202 when replacement stock is sold |
The practical use case: a founder receives a tender offer or secondary sale opportunity after holding for two years. The shares qualify as QSBS. If she can reinvest in a new qualifying company, she defers the gain and restarts the path toward permanent exclusion.
Four requirements to execute a §1045 rollover
1. The original stock must be QSBS
The shares you sell must have qualified as Section 1202 QSBS: original issuance from a domestic C corporation, gross assets at or below $50M (pre-July 5, 2025 issuance) or $75M (post-July 4, 2025 issuance), active business requirement, and eligible shareholder. See the full qualification checklist.
2. You held the original stock for more than 6 months
§1045 requires the original QSBS to have been held for more than six months before the sale date.2 Shares sold at 6 months or less are not eligible, regardless of gain size.
3. Reinvestment must happen within 60 days
You must purchase qualifying replacement QSBS within 60 days of the sale. The clock starts when proceeds are received, not when the transaction closes. There is no extension — the IRS has not granted blanket relief for missed §1045 windows the way it has for some other provisions.
4. The replacement stock must also be QSBS
The company you invest in must meet all §1202 requirements at the time you purchase the replacement shares — C corporation status, gross assets, active business, and original issuance. You cannot buy replacement QSBS on a secondary market; it must be newly issued stock.
Gross assets limits for replacement stock (OBBBA update)
The replacement stock must pass the §1202 gross assets test as of the date you buy it. The threshold depends on when the replacement company issues your shares:3
| Replacement stock issued | Gross assets test | §1202 exclusion cap if held 5+ years |
|---|---|---|
| Before July 5, 2025 | Company gross assets ≤ $50M at issuance | Greater of $10M or 10× adjusted basis |
| After July 4, 2025 (OBBBA)1 | Company gross assets ≤ $75M at issuance | Greater of $15M (inflation-adjusted from 2027) or 10× adjusted basis |
A company that previously exceeded the $50M threshold but has not yet reached $75M may issue QSBS for the first time after July 4, 2025 under the new cap. This matters when evaluating Series B or Series C stage companies as potential rollover targets.
How the math works: basis and partial rollovers
Full rollover
If you reinvest the entire sale proceeds into replacement QSBS, no gain is recognized in the year of sale. The deferred gain reduces the basis of the replacement stock. That reduced basis means more gain will be recognized — and potentially excluded — when you eventually sell the replacement stock.
Example A — Full rollover into new QSBS
| Sale proceeds from original QSBS (held 2.5 years) | $8,000,000 |
| Adjusted basis in original shares | $200,000 |
| Realized gain | $7,800,000 |
| Reinvested in replacement QSBS within 60 days | $8,000,000 |
| Gain recognized in year of sale | $0 |
| Basis in replacement stock ($8,000,000 − $7,800,000 deferred) | $200,000 |
If the replacement stock also qualifies as QSBS and is sold after the §1202 minimum holding period, the founder may exclude the entire $7,800,000 gain — including the previously deferred amount — at that future sale.
Partial rollover
You do not need to reinvest all proceeds. If you reinvest only a portion, you recognize gain equal to the proceeds not reinvested, up to your total realized gain. Reinvesting more than half of a large gain may still be worth modeling even if a full rollover is not practical.
Example B — Partial rollover (only $5M reinvested)
| Sale proceeds from original QSBS | $8,000,000 |
| Adjusted basis | $200,000 |
| Realized gain | $7,800,000 |
| Reinvested in replacement QSBS | $5,000,000 |
| Proceeds not reinvested | $3,000,000 |
| Gain recognized in year of sale | $3,000,000 |
| Gain deferred into replacement stock | $4,800,000 |
| Basis in replacement stock ($5,000,000 − $4,800,000) | $200,000 |
The $3M recognized gain is taxed in the year of sale. The $4.8M deferred into replacement stock may eventually be excluded if the replacement stock meets §1202 requirements at the future sale.
Holding period tacking: the path to §1202 exclusion
When you execute a §1045 rollover, your holding period in the replacement stock includes your holding period in the original stock for purposes of the §1202 five-year requirement.2 This is the most important planning benefit after the deferral itself.
| Scenario | Original hold | Time remaining to §1202 exclusion in replacement stock |
|---|---|---|
| Founder sold at 2.5 years, rolled into replacement QSBS | 2.5 years | 2.5 more years (tacked, 5-year total) |
| Angel sold at 1 year, rolled into replacement QSBS | 1 year | 4 more years (tacked) |
| Employee sold tender-offer shares at 3 years | 3 years | 2 more years |
This tacking applies for §1202 purposes because of the explicit carryover rule in §1045. It means a founder who sold at year 2.5, rolled over, and then held the replacement for another 2.5 years has effectively achieved the five-year holding period path — and the deferred gain from the original sale, now embedded in the replacement stock's basis, may be eligible for exclusion at the future sale.
The replacement stock must independently meet the §1202 "substantially all" active business test (80% or more of the combined holding period).4 A professional should model the basis tracking and holding period records before assuming the full deferred gain is excludable at the replacement-stock sale.
State tax: §1045 rollovers are not federally exclusive
Non-conforming states do not defer gain under §1045 any more than they exclude it under §1202. The gain you defer for federal purposes is taxable at the state level in the year of sale.
| State | §1045 deferral treatment |
|---|---|
| California | No conformity — gain taxable at 13.3% top rate in year of sale5 |
| Pennsylvania | No conformity — gain taxable in year of sale |
| Alabama, Mississippi | No conformity |
| New Jersey | Conforms to §1202 since Jan 2026 (A4455); §1045 conformity consistent with §1202 position but verify with NJ tax counsel |
| Most other states | Conform to federal §1045 treatment |
A California founder executing a $8M §1045 rollover still owes approximately $1.06M in California tax in the year of sale (13.3% on $7.8M recognized gain). This is not a reason to avoid the rollover — the federal deferral is typically worth far more — but the state bill must be funded from liquid assets at the time.
See the QSBS state tax guide for full conformity details by state.
Making the §1045 election: what the return requires
The §1045 rollover is not automatic. You must elect it on your federal income tax return for the year of sale and report it correctly. The key steps:
- Report the sale on Schedule D. On Form 8949, enter the sale and then a separate line showing the elected rollover amount as a loss adjustment (code X), reducing the recognized gain to the reinvested portion.
- Attach a statement to the return identifying the original stock sold (company, acquisition date, basis, sale date, proceeds) and the replacement stock acquired (company, acquisition date, cost, confirmation that replacement stock is QSBS).
- Keep written confirmation from the replacement company — typically a representation letter — that the shares qualified as QSBS at the time of issuance, the gross assets test was met, and the company was a domestic C corporation engaged in an active qualified business.
- Track the replacement stock's carryover basis and tacked holding period in your records. This carryover affects your §1202 exclusion calculation when you eventually sell.
Common mistakes that cost founders the deferral
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Waiting until after closing to look for replacement stock. The 60-day window starts when proceeds are received, not when you decide to execute the rollover. Founders who receive an unexpected secondary sale offer often miss the window because they are surprised by the timeline.
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Buying replacement stock on the secondary market. Only original issuance QSBS qualifies. Purchasing existing shares from another holder — even from the same company — does not meet the original issuance requirement in §1202(c)(1)(B).
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Not verifying the replacement company's gross assets before closing. A Series C stage company may look like a startup but could have already breached the $50M (pre-OBBBA) or $75M (post-OBBBA) gross assets cap. Request a representation before wiring capital.
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Forgetting state tax liquidity in year of sale. A California founder who defers $10M of federal gain and fails to set aside cash for the 13.3% California bill will have an unexpected tax payment due April 15. Factor this into cash flow before the wire goes out.
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Not tracking the embedded basis in replacement stock. The deferred gain reduces your replacement stock's basis permanently. If you sell the replacement stock in a non-QSBS transaction — because it failed a §1202 test, or you sold before five years without another rollover — the taxable gain will be larger than the nominal proceeds minus investment cost would suggest.
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Assuming §1045 covers the deferred gain if the replacement stock fails §1202. The rollover defers gain, not permanently. If the replacement company is later recharacterized (changed from C corp to LLC, excluded industry, etc.), the previously deferred gain may be accelerated. Work with counsel to monitor the replacement company's QSBS status.
When a §1045 rollover is worth pursuing
It is not always the right move. Three questions help sort cases quickly:
- Do you have a realistic replacement investment? Writing a check into a company you haven't evaluated just to hit the 60-day window is worse than paying the tax. The rollover only benefits you if the replacement stock is a viable investment — and ideally another path to §1202 exclusion.
- How large is the state tax drag? In California and other non-conforming states, the state tax is owed regardless. If the deal is under $2M of gain and you're in California, the rollover complexity may not be worth the federal deferral benefit. For seven-figure federal gains, the math almost always favors the rollover.
- Is the replacement investment stage-appropriate? Replacement QSBS must be issued by a company that passes the gross assets test — which limits your options to earlier-stage companies. A founder exiting a Series D startup needs to invest rollover proceeds in a seed or Series A company, not a comparably sized one.
Get matched with a QSBS advisor
Section 1045 rollovers involve a short window, basis tracking, holding period records, state-level cash planning, and replacement stock due diligence. A fee-only advisor who works with founder liquidity events can help model the federal and state tax outcome, identify replacement investment candidates, and build the post-exit plan before the 60-day window closes.
Sources
- IRS Rev. Proc. 2025-67 — OBBBA inflation adjustments and updated §1202 exclusion cap ($15M for post-July 4, 2025 stock)
- Cornell LII — 26 U.S. Code § 1045: Rollover of gain from qualified small business stock to another qualified small business stock
- IRS Publication 550 — Investment Income and Expenses (includes §1202 gross asset test rules)
- Cornell LII — 26 U.S. Code § 1202: Partial exclusion for gain from certain small business stock
- California Franchise Tax Board — California conformity to federal tax law (§1045 not conformed)
Tax values and conformity status verified June 2026. OBBBA enacted July 4, 2025 (Public Law 119-21). New Jersey §1045 conformity follows the state's updated §1202 position under A4455 (effective January 2026); verify with NJ tax counsel before relying on it.
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