Section 1045 Rollover

What Is a Section 1045 Rollover?

Section 1045 of the Internal Revenue Code allows individuals to defer capital gains from the sale of qualified small business stock (QSBS) by reinvesting the proceeds into replacement QSBS within 60 days of the sale. The key benefit: if you sell QSBS before meeting the five-year holding period required for the Section 1202 exclusion, you can roll the gain into new QSBS and continue the holding period toward the five-year mark.

Section 1045 provides a safety valve for QSBS holders who cannot meet the five-year holding requirement — for example, if the company is acquired before you have held the stock for five years. Rather than losing the QSBS benefit entirely, you can defer the gain by reinvesting in another qualifying company.

How the Section 1045 Rollover Works

Eligibility Requirements

To qualify for a Section 1045 rollover:

1. Original stock must be QSBS: The stock you sell must meet all Section 1202 QSBS requirements (C-corporation, under $75 million gross assets at issuance, active business, original issuance)
2. Held more than six months: You must have held the QSBS for more than six months (but less than five years — if you held for five years, you would use the Section 1202 exclusion instead)
3. Replacement stock must also be QSBS: The stock you purchase with the proceeds must be QSBS of another qualifying company
4. 60-day reinvestment window: You must purchase the replacement QSBS within 60 days of the sale

The Gain Deferral

The gain from the sale is not recognized immediately — it reduces the cost basis of the replacement QSBS. This means you defer the tax until you eventually sell the replacement stock. If you hold the replacement QSBS for long enough to meet the combined five-year holding period, you may qualify for the Section 1202 exclusion on the deferred gain.

Basis Adjustment

Your cost basis in the replacement QSBS is reduced by the amount of gain deferred. If you sold QSBS for $500,000 with a $100,000 basis (=$400,000 gain) and purchased $500,000 of replacement QSBS, the basis in the replacement stock would be $100,000 ($500,000 purchase price - $400,000 deferred gain).

Holding Period

The holding period of the original QSBS does not tack onto the replacement QSBS for Section 1202 purposes. The five-year clock starts fresh with the replacement stock. However, the gain is deferred, so you have additional time to accumulate the five-year holding period.

Practical Implications for Startup Employees

Acquisition Before Five Years

The most common scenario for a Section 1045 rollover is when your company is acquired before you have held your exercised shares for five years. If the acquisition proceeds include cash, you have 60 days to invest that cash into QSBS of another qualifying company to defer the gain.

Finding Replacement QSBS

The 60-day window is tight. You need to identify and invest in another C-corporation that meets the QSBS requirements — gross assets under $75 million, active business, and you must acquire stock through original issuance. This typically means investing directly in an early-stage startup (not buying shares on the secondary market). Angel investing or investing in a qualifying company you plan to join can work.

Partial Rollover

You do not have to roll over the entire amount. If you sell QSBS for $500,000, you can roll over $300,000 into replacement QSBS and recognize the gain on the remaining $200,000 in the year of sale. The partial rollover provides flexibility to take some liquidity while deferring the rest.

Documentation

Report the Section 1045 rollover on your tax return for the year of sale. Maintain documentation proving that both the original and replacement stock meet QSBS requirements, that the reinvestment occurred within 60 days, and the cost basis calculations.

How It Relates to Exercising Stock Options

Section 1045 is relevant to exercise planning when an exit is anticipated within five years of exercise. If you exercise stock options and receive QSBS, but the company is acquired before you reach the five-year holding mark, the Section 1045 rollover lets you defer the gain rather than paying taxes immediately. This makes exercising earlier (to start the QSBS clock) worthwhile even if a near-term acquisition is possible — if the acquisition happens before five years, you can roll the gain; if it happens after five years, you claim the full Section 1202 exclusion. Either way, exercising early positions you to benefit from the QSBS framework.