Section 1045 Rollover: How to Defer QSBS Gains and Keep the Clock Running

This post is part of my complete guide to QSBS and Section 1202.

Sarah Chen has a problem. She founded a SaaS company in Seattle three years ago, structured it as a C-corp from day one, and just received an acquisition offer she can't refuse — $8 million for her shares. Her stock qualifies as QSBS under Section 1202.

But she's only held it for three years. Under the OBBBA's tiered exclusion schedule, she can exclude 50% of her gain at three years, 75% at four, and 100% at five. If she sells now, she's leaving half her exclusion on the table — roughly $950,000 in federal tax she wouldn't owe if she could just wait two more years.

She doesn't want to pass on the deal. But she doesn't want to write a million-dollar check to the IRS either.

This is exactly the problem Section 1045 was designed to solve.

What Is a Section 1045 Rollover?

Section 1045 allows a taxpayer who sells QSBS to defer the gain by reinvesting the proceeds in new qualifying QSBS within 60 days. The original gain isn't recognized — it's rolled into the replacement stock by reducing your basis.

Think of it as a 1031 exchange for startup stock. You're not paying the tax now. You're pushing it forward into your next investment, where you can continue building toward the full five-year exclusion.

The Five Requirements

To qualify for a 1045 rollover, you must meet all five of these:

1. You must have held the original QSBS for at least six months. This is the minimum holding period — no exceptions. Stock held for five months and 29 days doesn't qualify.

2. You must reinvest in replacement QSBS within 60 days of the sale. The clock starts on the date of sale. There are no extensions. If day 61 arrives and you haven't closed on replacement stock, the rollover is gone.

3. The replacement stock must itself qualify as QSBS. It must be stock in a domestic C corporation with gross assets under $75 million (post-OBBBA), acquired at original issuance, in a company that meets the active business requirement.

4. You must reinvest at least as much as the gain you want to defer. If you sell for $8 million and have $7.5 million in gain, you need to reinvest $7.5 million in new QSBS to defer the entire gain. You can do a partial rollover if you reinvest less.

5. The replacement stock must be acquired for "cost." You must pay cash or property for the replacement stock — stock received for services (like a stock grant) does not qualify.

Holding Period Tacking: The Key Benefit

Here's what makes 1045 particularly powerful after the OBBBA: your original holding period carries over to the replacement stock.

Sarah held her original QSBS for three years. If she rolls into new QSBS, her holding period on the replacement stock starts at three years, not zero. She only needs two more years to reach the five-year mark for the full 100% exclusion.

Under the OBBBA's tiered schedule:

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If the replacement company succeeds and Sarah sells after two more years, she gets the full 100% exclusion on the deferred gain plus any new appreciation.

The Basis Adjustment

When you roll over, your basis in the replacement stock is reduced by the amount of deferred gain. This is how the IRS tracks what you owe.

Sarah's math:

- Original QSBS cost basis: $500,000

- Sale price: $8,000,000

- Gain: $7,500,000

- Amount reinvested in new QSBS: $8,000,000

- Basis in replacement QSBS: $8,000,000 - $7,500,000 = $500,000

Sarah's replacement stock has a basis of $500,000, even though she paid $8 million for it. The $7.5 million in deferred gain is embedded in that low basis and will be recognized when she eventually sells — unless she qualifies for a Section 1202 exclusion at that point.

The Angel Investor Play

Section 1045 isn't just for founders. Angel investors use it to manage portfolio risk while preserving QSBS benefits.

David Park is a Seattle angel investor. He invested $100,000 in a startup two years ago. The company just received an acquisition offer valuing his shares at $600,000. He's only at two years — short of the three-year minimum for any OBBBA exclusion. But he's past the six-month minimum for a 1045 rollover.

David sells for $600,000, then reinvests $500,000 (the gain amount) in another qualifying startup within 60 days. His $500,000 gain is deferred. His holding period tacks. In three more years (five total from original acquisition), he can sell the replacement stock and exclude the gain entirely under Section 1202.

Washington State Implications

For Washington residents, the 1045 rollover is especially valuable. Deferred gains are not included in federal AGI, which means they don't trigger Washington's 7% capital gains tax or the new 9.9% income tax. You're deferring state tax as well as federal.

The 60-Day Trap

The single biggest mistake I see with 1045 rollovers: missing the 60-day window. Founders close a sale, deposit the proceeds, start looking for their next investment — and suddenly it's day 55 and they haven't found qualifying replacement stock.

My advice: identify your replacement QSBS investment before you sell. Have the term sheet ready. Know that the company qualifies. Don't start the 60-day clock until you have a plan to stop it.

*For the complete Section 1045 playbook — including advanced strategies for serial entrepreneurs, portfolio construction for angel investors, step-by-step basis calculations, Washington State tax analysis, and detailed checklists — get the Section 1045 QSBS Rollover Guide.*

*Have questions about whether a 1045 rollover makes sense for your situation? Book a 20-minute intro call.*

For the complete Section 1045 playbook with advanced strategies, checklists, and worked scenarios, get the Section 1045 QSBS Rollover Guide.

Have questions? Book a 20-minute intro call.

Section 1045 in Plain English

Section 1045 solves a specific problem: you sold QSBS before the five-year mark and now face a taxable gain. Without Section 1045, that gain is fully taxable — you lose the Section 1202 exclusion entirely. With Section 1045, you can defer the gain by reinvesting the proceeds into new QSBS within 60 days.

Think of it as a QSBS reset button — but only if you move quickly and follow the rules precisely.

Who Uses Section 1045 — and When

Section 1045 is most relevant in three situations:

• Early secondary sales: An angel investor sells their stake in a secondary transaction before the five-year mark. Instead of paying tax on the gain, they reinvest in another qualifying startup.
• Founder liquidity events: A founder takes partial liquidity in a tender offer or secondary sale before reaching five years of QSBS holding.
• Portfolio recycling: An angel investor or small fund systematically rolls gains from early exits into new qualifying investments, deferring tax indefinitely and compounding returns.

The strategy is especially powerful for active angel investors who are continuously deploying capital — each rollover defers tax and the new QSBS begins its own five-year clock toward a permanent Section 1202 exclusion.

The Section 1045 Process Step by Step

1. Confirm QSBS status: The stock you're selling must qualify as QSBS — issued by a domestic C-corp with gross assets under $50M, held for more than six months (but less than five years).
2. Sell the stock: Complete the sale. The 60-day clock starts on the date of sale, not the date you receive proceeds.
3. Identify replacement QSBS: You must reinvest in stock of a different qualified small business. You cannot roll into the same company. The replacement company must independently meet all Section 1202 requirements at the time of your investment.
4. Reinvest within 60 days: The entire proceeds (not just the gain) must be reinvested. Partial rollovers result in partial gain recognition. The 60-day deadline is absolute — no extensions.
5. Elect Section 1045 on your return: Report the rollover on Schedule D of your tax return. The election is made on the return for the year of the sale.

Section 1045 vs. Section 1202: How They Work Together

Section 1202 and Section 1045 are complementary, not competing, strategies.

• Section 1202 permanently excludes gain after five years — the gold standard. No tax on up to $10M–$15M in gain.
• Section 1045 defers gain when you sell before five years — a bridge strategy. The gain doesn't disappear; it carries over to the replacement stock, reducing its basis.

The best outcome: use Section 1045 to defer a short-term gain, hold the replacement QSBS for five years, and then use Section 1202 to exclude it permanently. The deferred gain from the rollover converts into permanently excluded gain.

The Basis Trap: What Most Guides Miss

When you do a Section 1045 rollover, the deferred gain reduces your basis in the replacement QSBS. This matters in two ways:

1. Lower basis = more gain to exclude under Section 1202. If you pay $100,000 for replacement stock and rolled over a $400,000 gain, your adjusted basis is $0 (not $100,000 — actually negative, but floored at zero for most purposes). When you later sell for $1M and claim the Section 1202 exclusion, you're excluding more gain.
2. The 10x basis calculation changes. Section 1202's alternative cap is 10x your adjusted basis. A lower adjusted basis from a rollover can reduce this alternative cap — though for most early-stage investors, the $10M/$15M flat cap is the relevant limit anyway.

Model both scenarios carefully with a tax advisor before executing a rollover if your basis in the replacement stock will be significant.

Related: QSBS pillar