The §1045 QSBS Rollover: Deferring Capital Gains for Serial Entrepreneurs

How to sell one qualified small business, reinvest in the next, and potentially eliminate the capital gains tax entirely.

If you've founded and sold a company — or you're in the process of doing so — there's a reasonable chance you're about to owe a significant capital gains tax bill. For a founder selling stock in a C corporation with meaningful appreciation, that tax can easily run into the hundreds of thousands or even millions of dollars at combined federal and state rates.

Most founders have heard of Section 1202, which can exclude up to $10 million (or ten times your adjusted basis, whichever is greater) of gain on the sale of qualified small business stock held for at least five years. It's a powerful provision, and it gets a lot of attention.

But what if you haven't held the stock for five years? What if a liquidity event comes at year two, or year three? That's where Section 1045 comes in — and it's the provision that most founders, and frankly many advisors, overlook entirely.

What Section 1045 Does

Section 1045 allows an individual taxpayer to defer the recognition of capital gain from the sale of qualified small business stock (QSBS), provided two conditions are met: the taxpayer held the stock for more than six months before the sale, and the taxpayer reinvests the sale proceeds into new QSBS within 60 calendar days of the sale.

Notice the holding period requirement. Section 1202 requires a five-year hold. Section 1045 only requires six months and a day. This is what makes it so useful when a liquidity event arrives ahead of schedule — it gives serial entrepreneurs a way to defer the tax instead of paying it, with the option to eventually eliminate it altogether through §1202 if the replacement stock is held long enough.

Key distinction: Section 1045 is a deferral mechanism, not an exclusion. The gain doesn't disappear — it gets embedded in the replacement stock through a basis reduction. But when combined with Section 1202, that deferred gain can ultimately be excluded from income entirely.

The Eligibility Requirements

Before you can use §1045, the stock you're selling must qualify as QSBS. This means it must be stock in a domestic C corporation that had aggregate gross assets of $50 million or less at the time the stock was issued. The stock must have been acquired at original issuance — meaning you got it directly from the company in exchange for money, property, or services (not purchased on the secondary market). And the corporation must have used at least 80% of its assets in one or more active trades or businesses during substantially all of the time you held the stock.

These are the same foundational requirements that apply under Section 1202. If your stock qualifies as QSBS for §1202 purposes, it qualifies for §1045 as well — the only difference is the holding period threshold.

The Replacement Stock Rules

The replacement stock must also be QSBS. Specifically, it must be newly issued stock in a different domestic C corporation that independently satisfies the gross asset test (under $50 million), the active business requirement (at least 80% of assets in active use), and the original issuance requirement. You cannot roll the gain into stock purchased on the open market, into stock of the same company you just sold, or into stock of an S corporation or partnership.

The replacement corporation must meet the active business test for at least the first six months after issuance — though it's not required to remain an active business indefinitely after that period for the rollover itself to remain valid.

The 60-Day Window

This is where the stakes get high. The reinvestment must occur within 60 calendar days of the date of the sale. Not the date you receive the proceeds. Not the date the deal was signed. The date of the actual sale — typically the closing date.

There is no extension, no grace period, and no reasonable cause exception. If escrow delays push your proceeds past the 60-day mark, you still had to have purchased replacement stock within the window. This is why planning must start before the sale closes, not after.

As a practical matter, this means you need to have identified replacement QSBS — and ideally have the investment documentation substantially ready — before your sale transaction closes. The 60-day constraint is often cited as the single biggest impediment to successfully executing a §1045 rollover.

Basis Adjustment and Holding Period Tacking

When you execute a §1045 rollover, two important things happen to your replacement stock.

First, the basis in your replacement stock is reduced by the amount of gain deferred. This is how the tax code ensures the deferred gain doesn't simply vanish — it's carried forward in the form of a lower basis, meaning you'll recognize more gain when you eventually sell the replacement stock (unless §1202 exclusion applies at that point).

Second, your holding period for the replacement stock includes the period you held the original stock. This is critical for the §1045-to-§1202 pipeline discussed below. If you held your original stock for two years and then executed a §1045 rollover, your replacement stock is treated as if you've already held it for two years from day one. You only need to hold it for three more years to reach the five-year threshold for §1202 exclusion.

The §1045-to-§1202 Pipeline

This is where the real planning power of §1045 becomes clear. Used on its own, §1045 is a deferral — useful, but the tax bill still exists somewhere down the line. Combined with §1202, however, §1045 becomes a bridge to full exclusion.

Here's how the pipeline works: you sell QSBS that you've held for more than six months but less than five years. Instead of paying the capital gains tax, you reinvest the proceeds into new QSBS within 60 days and defer the gain under §1045. You then hold the replacement stock for enough additional time — with your original holding period tacked on — to reach the five-year mark. When you sell the replacement stock, the entire gain, including the deferred portion from the original sale, is eligible for the §1202 exclusion.

Worked Example: The §1045-to-§1202 Pipeline

Sarah founds TechCo (a C corporation with under $50M in gross assets) in January 2023. She invests $200,000 for her founding shares. In September 2025 — two years and eight months later — she sells her stock for $3,200,000. Her capital gain is $3,000,000.

Sarah has held the stock for more than six months, so she qualifies for a §1045 rollover. Within 60 days of the sale, she invests the full $3,200,000 into shares of NextVenture Inc., another qualifying C corporation.

The Numbers:

Sale price of TechCo stock: $3,200,000
Basis in TechCo stock: $200,000
Capital gain (deferred under §1045): $3,000,000
Amount reinvested in NextVenture: $3,200,000
Adjusted basis in NextVenture (reduced by deferred gain): $200,000
Holding period tacked from TechCo: 2 yrs, 8 mos

Sarah holds NextVenture for another 2 years and 4 months, reaching a total tacked holding period of 5 years. She then sells her NextVenture stock for $5,000,000.

Scenario Comparison:

No planning — pays tax on TechCo sale in 2025: ~$714,000
§1045 only — defers TechCo gain, pays on NextVenture sale: ~$1,142,000
§1045 → §1202 pipeline — excludes entire gain: $0

The §1045-only figure assumes 23.8% combined federal rate on total gain of $4,800,000 ($5M sale minus $200K adjusted basis). The pipeline figure assumes gain is within the greater-of-$10M-or-10x-basis exclusion ceiling. State taxes may still apply in non-conforming states.

The numbers speak for themselves. The §1045-to-§1202 pipeline doesn't just defer the tax from the original sale — it creates a path to eliminating it entirely, along with the gain on the replacement stock.

Want to model your own numbers? Use our interactive §1045 Rollover Planner.

Partial Rollovers

You don't have to reinvest the full amount. Section 1045 allows partial rollovers — you recognize gain only to the extent the sale proceeds exceed what you reinvested in replacement QSBS. If you sell stock for $3 million and reinvest $2 million into new QSBS within 60 days, you defer $2 million of gain and recognize $1 million immediately (assuming the entire $3 million was gain).

This flexibility can be useful if you want to take some liquidity off the table while still deferring the bulk of the tax.

The Traps

Section 1045 is powerful, but the margin for error is thin. Here are the most common ways it goes wrong:

Missing the 60-day window. This is non-negotiable. If you close on Day 1 and don't complete the reinvestment by Day 60, the deferral is lost. Escrow holdbacks, delayed wires, and due diligence on the replacement investment all eat into this window. Start identifying replacement QSBS before your sale closes.

Replacement stock that doesn't qualify. Every element of the QSBS test must be satisfied independently by the replacement company. If the replacement corporation's gross assets exceeded $50 million at the time of issuance, or if it fails the active business requirement, or if you're buying shares on the secondary market rather than at original issuance — the rollover fails and the deferred gain becomes taxable retroactively.

Partnership and S-corp complications. Section 1045(b)(5) contains special rules for QSBS held through pass-through entities. The mechanics are more complex, and the election to defer gain is made at the partner or shareholder level, not the entity level. This is an area where the technical requirements can trip up even experienced advisors.

State non-conformity. Several states do not recognize the §1045 rollover or the §1202 exclusion at the state level. California is the most significant — it taxes QSBS gains at full state rates regardless of the federal treatment. Pennsylvania, Mississippi, and Alabama also have conformity gaps. If you're a resident of a non-conforming state, you may owe state capital gains tax even on a properly executed federal rollover.

Who Should Be Thinking About This

The §1045 rollover is designed for a specific type of taxpayer: someone who founded or invested in a qualifying C corporation, held the stock for at least six months, and is facing a liquidity event before the five-year §1202 window has elapsed. In practice, this most often looks like a serial entrepreneur who is selling one venture and rolling the proceeds into the next, or a founder who receives an acquisition offer earlier than expected.

If that describes your situation — or if you're planning a sale that might close in the next 6 to 12 months — the time to start planning is now, not after closing. The 60-day window doesn't leave room for retroactive strategy.

If you've recently sold QSBS or have a sale on the horizon, we can help you evaluate your §1045 eligibility, identify replacement QSBS, and structure the rollover to set up the §1202 exclusion. You can also explore the numbers yourself with our §1045 Rollover Planner.

Book a consultation with our team.

Disclaimer: This article is for informational purposes only and does not constitute legal or tax advice. The application of §1045 and §1202 depends on individual facts and circumstances. Consult a qualified tax attorney or CPA before making decisions based on this information. Circular 230 Notice: To ensure compliance with requirements imposed by the IRS, we inform you that any U.S. federal tax advice contained in this communication is not intended or written to be used, and cannot be used, for the purpose of avoiding penalties under the Internal Revenue Code.

R Jason Griffin | Mar 10 2026 16:54