You sold your shares at year three. The acquirer wired the cash. Your CPA called two weeks later with the bad news: because you didn't hit the five-year hold, your QSBS exclusion is gone — and you owe ~23.8% federal tax on every dollar of gain.

That story is wrong. Or at least, it doesn't have to end that way.

Section 1045 of the Internal Revenue Code lets you take the proceeds from a QSBS sale and roll them into new qualified small business stock within 60 days. Do it right, and you defer the full gain. Your holding period carries over. The QSBS clock keeps ticking — it does not restart.

The One Big Beautiful Bill Act (OBBBA) didn't touch §1045. What it did change was the math on when to roll. Founders acquiring stock on or after July 5, 2025 can now claim a 50% exclusion at year 3, a 75% exclusion at year 4, and 100% at year 5. That makes the §1045 rollover a more interesting tool than it has been in a decade — especially for early exits, secondaries, and forced-liquidity events.

This is a guide for founders who want to know how section 1045 qsbs rollovers actually work, what qualifies as "replacement QSBS," and when rolling beats waiting.

What is a Section 1045 rollover?

Section 1045 is a gain-deferral provision for qualified small business stock. Sell QSBS that you've held for at least six months, reinvest the proceeds into new QSBS within 60 days, and you defer the gain instead of recognizing it.

The basic mechanic

Three moving pieces:

  1. Sell QSBS that you've held for more than six months.
  2. Reinvest some or all of the proceeds into replacement QSBS within 60 days of the sale.
  3. File a §1045 election on your tax return for the year of the sale.

The gain doesn't disappear — it attaches to the replacement stock. Your basis in the new stock is reduced by the amount of gain you rolled over. When you eventually sell the replacement stock, the deferred gain surfaces.

Defer versus exclude: §1045 is not §1202

Founders sometimes conflate these two sections because they both reference QSBS. They do very different things.

  • §1202 is the exclusion. If you meet the five-year holding period (or the new OBBBA tiers), you can exclude up to $15M of gain per taxpayer — potentially forever tax-free.
  • §1045 is the deferral. If you sell before the holding period is complete, you can push the gain forward into a new QSBS and keep the clock running.

Together, they compound. You can use §1045 now to survive an early exit and use §1202 later to exclude the gain once the holding period catches up. Unlike §1202's per-taxpayer cap, §1045 has no dollar limit on the amount you can roll over.

Who this is actually for

§1045 is the right tool when:

  • Your company was acquired before you hit 5 years and the acquirer isn't issuing QSBS
  • You need liquidity (tender offer, secondary sale) but still want to preserve QSBS treatment
  • You're a repeat founder raising capital for a new venture and want to reinvest exit proceeds
  • An unsolicited offer came in at year 2 or 3 and the math on sell-and-roll beats holding out

If you've already crossed 5 years on your original stock, you don't need §1045. Take the §1202 exclusion and move on. §1045 earns its keep when the timing is wrong but the opportunity is right.

The five requirements for a §1045 rollover

The rules are specific. Miss one and the election fails — meaning the gain is recognized in the year of sale at whatever capital-gains rate applies to your situation.

1. The original stock must qualify as QSBS

Before you can roll, the stock you sold has to meet the §1202 requirements: issued by a domestic C-corporation, acquired at original issuance, with gross assets under the applicable threshold at issuance ($50M pre-OBBBA, $75M post-OBBBA), and the company must have been in an active trade or business that isn't on the excluded list (professional services, financial services, hospitality, real estate, extraction, etc.).

If your original stock wasn't QSBS to begin with, §1045 isn't available to you. There's no retroactive fix.

2. Six-month minimum holding period

You have to have held the original QSBS for more than six months before the sale. This is a shorter hurdle than §1202's full holding period — §1045 exists precisely to help founders who didn't get to 3, 4, or 5 years.

Six months is the floor, not a target. Sell at day 179 and you've forfeited the rollover entirely.

3. The 60-day reinvestment window

You have 60 days from the date of sale to purchase replacement QSBS. There are no extensions. There is no hardship provision. On day 61, the rollover is gone.

This is the practical bottleneck of §1045 — not the statute itself, but the logistics. Finding a replacement QSBS that meets all the §1202 requirements inside a two-month window is not trivial. As Frost Brown Todd puts it:

"Any actions taken regarding Section 1045 typically need to be arranged long before the 60-day reinvestment window even begins."
— Frost Brown Todd, §1045 primer

Practical implication: if you see an early liquidity event coming, start diligencing replacement-QSBS candidates before the sale closes, not after.

4. The replacement stock must qualify as QSBS

Most failed rollovers break here. The replacement stock has to meet all the same §1202 tests the original stock met — issued by a domestic C-corp, at original issuance, with qualifying gross assets, in a qualifying trade or business.

One specific trap: the replacement issuer must satisfy the active-business requirement for at least 6 months after issuance. A newly formed C-corp that sits on cash for its first six months can fail this test — and that failure voids your rollover.

5. A timely election

You make the §1045 election by attaching a statement to your timely filed tax return (including extensions) for the year of the sale. The procedure is laid out in Rev. Proc. 98-48. The election is per-taxpayer and per-sale.

Miss the filing, file the wrong statement, or file late, and the deferral is lost.

How §1045 interacts with OBBBA's tiered exclusion

Here's what most founder-facing content misses: OBBBA did not amend §1045. The 6-month hold, the 60-day window, the election mechanics — all unchanged.

What OBBBA changed is the §1202 exclusion schedule that your deferred gain eventually flows into. That changes the strategic question from "can I roll?" to "should I?"

The split-regime problem

OBBBA is prospective. Stock issued on or before July 4, 2025 operates under the legacy rules: $10M per-taxpayer cap, five-year hold for 100% exclusion, $50M gross-asset ceiling. Stock issued on or after July 5, 2025 operates under the new rules: $15M cap, tiered holding periods (50% at 3 years, 75% at 4 years, 100% at 5 years), and a $75M gross-asset ceiling.

This creates a real wrinkle for rollovers. Current tax commentary holds that a §1045 rollover does not reset the exclusion-percentage regime — the percentage that eventually applies to your deferred gain is generally tied to the vintage of your original QSBS, not the replacement. If your original stock was acquired in 2023, the deferred gain is generally understood to remain under pre-OBBBA rules even while you're sitting inside post-OBBBA replacement stock. The IRS has not yet issued formal guidance on this specific OBBBA interaction, so coordinate with your CPA before relying on the default rule.

Work with your CPA to map the vintage of each tranche. It materially affects the exit math.

The year-3 roll-forward play

For founders with post-OBBBA stock, the tiered exclusion introduces a scenario that didn't exist before: a partial exit at year 3 that doesn't forfeit QSBS treatment.

Say you acquired QSBS after July 5, 2025 and an unsolicited acquisition offer lands at year 3. Under the new tiers, you can:

  • Take the 50% exclusion on gain up to the $15M cap
  • Roll the remainder into replacement QSBS under §1045
  • Keep the clock ticking on the rolled-over portion, with your holding period carrying forward

That's a scenario the pre-OBBBA rulebook never allowed — and it's the most interesting reason to study §1045 right now.

Sell and roll, or hold to five

The decision comes down to four variables:

  • Your confidence in the replacement QSBS. A §1045 rollover only makes sense if you can actually find a replacement company you believe in. Rolling into a shaky target to defer tax is a bad trade.
  • Liquidity pressure. If you need the cash for life reasons (house, divorce, health), rolling isn't an option — it consumes the proceeds.
  • Current exclusion tier. Under OBBBA, a 50% exclusion at year 3 might be enough to make the after-tax proceeds attractive without rolling.
  • The vintage math. Pre-OBBBA stock deferred into a post-OBBBA replacement doesn't upgrade regimes. Plan accordingly.

Three worked examples

Example 1: Year-3 rollover under OBBBA tiers

You acquired QSBS in September 2025 at a basis of $50,000. Three years later, an acquirer offers you $20M in cash for the shares.

  • Gain: $20M − $50,000 = $19.95M
  • 50% OBBBA exclusion (3-year tier): ~$9.98M excluded
  • Remaining ~$9.98M taxable — as "Section 1202 gain" at a 28% federal rate plus 3.8% NIIT (~31.8% combined), unless you roll it forward

Quick note on the rate: the non-excluded portion of a partial §1202 exclusion isn't taxed at the standard 20% LTCG rate. Under IRC §1(h)(7), it's "Section 1202 gain" and caps out at a 28% federal rate. With NIIT on top, assume ~31.8% for back-of-the-envelope math on the 3-year and 4-year tiers. The 5-year tier (100% exclusion) has no non-excluded portion, so the rate question doesn't come up.

Option A: Take the 3-year exclusion only.

  • Pay ~31.8% on ~$9.98M = ~$3.17M in federal tax
  • Net after-tax: ~$16.83M

Option B: Take the 3-year exclusion on half and roll the taxable half into replacement QSBS.

  • Pay ~$0 federal tax this year on the rolled portion
  • Hold replacement QSBS until the original holding period crosses 5 years
  • Potentially exclude the full deferred gain under §1202 at exit

Option B keeps more capital working tax-deferred. Option A is simpler and fully closes the chapter on the exited company. The spread is roughly $3.17M in near-term tax versus deferral that could ultimately be 100% excluded. Neither is universally correct — it depends on your conviction in the replacement and your need for liquidity.

Example 2: Partial rollover for liquidity

You sell $8M of pre-OBBBA QSBS at year 4 — before your §1202 five-year hold is complete. You need $3M for a house and want to defer the rest.

  • Cash you keep: $3M (fully taxable — you'll owe ~$714K in federal tax, assuming near-zero basis)
  • Amount rolled into replacement QSBS: $5M
  • Deferred gain: allocated proportionally to the rolled portion
  • Basis in replacement stock: $5M minus the deferred gain

This is the everyday shape of a §1045 rollover for most founders — partial, pragmatic, and driven by a real liquidity need rather than a pure tax play.

Example 3: §1045 and non-grantor trust stacking

You've put QSBS into a non-grantor trust two years before an early exit. The trust owns the stock when the sale closes. Each non-grantor trust is its own taxpayer under the tax code — so it has its own QSBS exclusion and its own ability to do a §1045 rollover.

If the sale lands before the trust's holding period is complete:

  • The trust can make its own §1045 election
  • Deferred gain rolls into replacement QSBS held by the trust
  • The holding period tacks (IRC §1223(13)) — the trust's acquired date carries forward
  • When the replacement stock eventually exits with a full 5-year hold, the trust can use its own QSBS exclusion against the deferred gain

Combine a trust-held §1045 rollover with a founder-held §1045 rollover and you can compound the benefit across multiple taxpayers — each with its own deferral and eventual exclusion.

The trust interaction is rarely covered in founder-facing §1045 content. It's also the reason many founders who do trust planning early don't have to choose between §1045 and trust stacking — they can use both.

Learn more about how QSBS trust stacking works and how it pairs with OBBBA's tiered exclusion.

The most common §1045 mistakes

Real rollovers fail in predictable ways.

Missing the 60-day window

The deadline is the date of sale, not the date of closing paperwork or the date the wire cleared. Earnouts and installment payments muddy this further — the 60-day clock on deferred consideration is a gray area that hasn't been cleanly resolved in case law or guidance. If your deal has an earnout, coordinate closely with your CPA on whether each installment triggers a separate 60-day window.

Buying replacement stock that doesn't actually qualify

"Replacement QSBS" isn't every C-corp under $75M. The issuer has to be in a qualifying trade or business and has to actively conduct that business for at least 6 months after issuance.

The cautionary tale is John P. Owen v. Commissioner (TC Memo 2012-21). A taxpayer rolled the proceeds of a prior QSBS sale into a newly formed jewelry-reseller C-corp, held 92% of assets in cash, purchased just 16 pieces of jewelry (total cost under $150,000) in its first six months, and recorded only six sales (three to related parties) in its first year. The Tax Court disallowed the rollover. The replacement company wasn't really in business — it was parking cash.

A related trap is the 2-year working-capital cliff under §1202(e)(6). After two years, no more than 50% of the replacement corporation's assets can qualify as "working capital." Fund a replacement C-corp with $10M of rollover proceeds and leave it sitting in a money-market fund while you search for an acquisition target, and the math quietly breaks.

Losing track of carryover basis and holding period

Your basis in the replacement stock is reduced by the rolled gain. Your holding period from the original stock tacks onto the replacement. When you eventually sell the replacement, both numbers matter for the §1202 exclusion.

Track this in writing at the time of the rollover — not five years later when you're preparing for a second exit.

Filing the election incorrectly — or not at all

The §1045 election is made by attaching a specific statement to your timely filed return (including extensions) under Rev. Proc. 98-48. The statement has required content. It's not a checkbox on a form. A CPA who hasn't filed a §1045 election before is not the right person to improvise.

Decision matrix: when to roll vs. take the exclusion

Rolling is not always the right answer. A quick gut check:

Roll when:

  • You're forced into an early exit (acquisition before the holding period is complete, acquirer not issuing QSBS)
  • You're a repeat founder with a credible replacement target already in view
  • You have strong conviction in the replacement company's QSBS status and active business
  • Your vintage math means rolling preserves meaningful future exclusion

Take the exclusion when:

  • Your 5-year hold is already complete (you don't need §1045)
  • The OBBBA 3-year or 4-year tier already gets you to acceptable net proceeds
  • You have no replacement candidate you're genuinely comfortable with
  • You need the liquidity and can't reinvest the proceeds

Don't roll when:

  • The replacement is a shell C-corp without a real business
  • You can't complete the replacement purchase inside 60 days
  • The basis math and holding-period tracking would be too fragile to defend at audit

Conclusion

§1045 is the tool that makes QSBS resilient to timing. An early exit doesn't have to cost you your exclusion — if you know the rules and act inside 60 days.

Three things to take away:

  • §1045 defers — it doesn't exclude. The deferred gain eventually surfaces. The benefit is that your holding period tacks onto the replacement, so you can still earn the §1202 exclusion later.
  • 60 days is firm. Start diligencing replacement QSBS before you sell, not after.
  • OBBBA changed the decision math, not §1045 itself. The new 3-year and 4-year exclusion tiers make partial exits plus rollovers a genuinely interesting play for founders with post-July-2025 stock.

A §1045 rollover done right can preserve tens of millions in QSBS benefit that would otherwise evaporate in an early exit. Done wrong — wrong replacement stock, missed window, botched election — it does nothing.

If you're looking at an early liquidity event and want to understand whether a §1045 rollover fits your situation, schedule a call to model your scenario. We help founders pressure-test replacement-QSBS candidates, coordinate the 60-day window, and make sure the election is filed correctly the first time.

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