QSBS Packing: The Complete Guide to the 10x Basis Cap

Section 1202 gives qualifying founders a federal tax exclusion of up to $10 million per taxpayer, per issuer. For stock acquired after July 4, 2025, that cap rises to $15 million. For founders planning a $50 million, $80 million, or $150 million exit, that flat dollar cap runs out fast.

QSBS packing is the strategy that changes that math.

QSBS packing is the practice of intentionally increasing your adjusted basis in Qualified Small Business Stock (QSBS) at original issuance. Here is why that matters:

Under Section 1202, your exclusion cap for a given tax year is whichever is greater: the flat dollar cap, or 10 times the aggregate adjusted basis of the shares of that company you sell during that year, measured at original issuance.¹ Most founders receive their shares for a nominal amount, so the flat cap ($10 million or $15 million) almost always applies. Packing changes that.

By raising your basis at issuance, you activate the 10x calculation. A $5 million basis means a $50 million exclusion ceiling. A $10 million basis means a $100 million exclusion ceiling. The table below shows how this plays out across different scenarios.

The 10x Basis Cap in Action

Source: Keystone Global Partners, illustrative example (2026)

For purposes of the 10x test, adjusted basis is fixed at original issuance. Any addition to basis after that date is disregarded, including later capital contributions to the company.²

Three Kinds of Basis, and Which One Packing Moves

“Basis” means three different numbers in a QSBS analysis, and they rarely match. Keeping them separate is the difference between a packing plan that works and one that only looks like it does.

Packing moves the second number. It only works if the third number stays under the threshold, and the first number still determines your total gain on the sale.

Example: Your basis in your LLC interest is $500,000 and you convert when the company is worth $8 million. Your regular tax basis in the new shares carries over at $500,000, so a later $88 million sale produces $87.5 million of gain. Your Section 1202 basis is $8 million, so your 10x cap is $80 million and only the $80 million of appreciation above $8 million is eligible for exclusion; the $7.5 million below it is taxed. The company’s gross assets after conversion count the contributed property at $8 million, not $500,000, which is comfortably under $75 million.

LLC-to-C-Corp Conversion

If you built your company as an LLC before converting to a C corporation, Section 1202 treats your new shares as having a basis of no less than the fair market value of the property you contributed at conversion.⁶ That higher starting basis can significantly raise your 10x exclusion cap.

Example: You convert your LLC when it is worth $8 million. Your new C corp shares carry an $8 million Section 1202 basis, so your 10x exclusion cap becomes $80 million. If you later sell for $88 million, the $80 million of post-conversion appreciation is eligible for exclusion. The first $8 million of value, less your actual basis in the LLC, is taxed as ordinary capital gain with no Section 1202 benefit.

What to watch:

Pre-conversion gains do not qualify.

Any appreciation that occurred while the company operated as an LLC is not excludable under Section 1202. Only gains that accrue after conversion are eligible. This is one of the most important caveats in any packing analysis. How the conversion is executed (a check-the-box election, a contribution of assets, or a contribution of LLC interests) changes the basis and holding period mechanics and should be chosen deliberately.

The QSBS clock starts at conversion.

Your holding period begins on the date of conversion, not when you originally founded the LLC. For conversions after July 4, 2025, that means three years to reach the 50% tier, four for 75%, and five for 100%.⁷

The gross assets test applies at issuance.

The company’s aggregate gross assets (cash plus the adjusted tax basis of other property) must not have exceeded the threshold at any time before the conversion, and must not exceed it immediately after. Critically, property contributed in the conversion is counted at its fair market value at the time of contribution, not its historic tax basis.⁸ An LLC worth more than the threshold at conversion cannot produce QSBS. The threshold is $50 million for stock issued on or before July 4, 2025 and $75 million for stock issued after that date.⁹

Downside risk is real.

If the company converts at a high valuation but exits at a lower-than-expected price, you may owe significant tax on the pre-QSBS appreciation with little exclusion to offset it. In some scenarios, this leaves you worse off than if you had started as a C-corp from day one.

The cap is per taxpayer, so count the founders.

Basis from a conversion is split among the owners in proportion to their interests, and each founder’s 10x cap is computed on their own share. Two cofounders who convert a $2 million LLC each receive $1 million of Section 1202 basis and a $10 million 10x cap, which is below the $15 million flat cap, so the conversion packs nothing. For two equal founders the conversion value has to exceed $3 million before the 10x cap does any work; for three equal founders, $4.5 million. The threshold is $1.5 million of basis per founder, whatever the headcount.¹⁰ The trade-off is unchanged: every dollar of conversion value is pre-conversion gain that will be taxed without any exclusion.

This strategy works best when there is a long runway between conversion and exit, and when post-conversion growth is expected to be substantial.

Cash Contribution at Original Issuance

The most straightforward packing method: contribute cash to the company when you receive your QSBS shares. Each dollar you contribute increases your adjusted basis dollar-for-dollar.

Example: You contribute $3 million in cash at issuance. Your basis is $3 million. Your 10x exclusion cap becomes $30 million.

There is no pre-contribution built-in gain problem with cash. The cash must be paid for newly issued shares acquired directly from the company for it to count under the 10x test. Cash contributed to the company later, without receiving new shares, increases your tax basis but is disregarded for the 10x cap.¹¹

The trade-off is liquidity. You are deploying real capital into the company rather than keeping it accessible elsewhere. That decision needs to fit your broader financial plan.

Two company-level checks before you wire the money. First, the gross assets test is measured immediately after the issuance and includes the cash you just contributed. A $10 million contribution to a company carrying $68 million of tax-basis assets pushes it past $75 million and the new shares are never QSBS.¹² Second, the company must use at least 80% of its assets in an active business for substantially all of your holding period. Contributed cash qualifies only if it is reasonably required working capital or reasonably expected to be deployed within two years into research or working capital needs, and after the company’s second year no more than 50% of its assets can qualify under that safe harbor.¹³ Cash that sits unspent can jeopardize the active business test.

You do not have to pack on day one.

Original issuance means the shares you buy directly from the company, not the day the company was formed. A founder can purchase newly issued shares for cash in a later priced round and establish basis in those shares. Because the 10x calculation aggregates the basis of all shares of that issuer you sell in the same tax year, selling founder shares and later-purchased shares together in one year produces a combined cap.¹⁴

Example: You hold founder shares with $50,000 of basis. In the Series B you buy $3 million of newly issued preferred directly from the company. Five years later you sell both blocks in the same tax year. Your 10x cap for that year is $30.5 million, not $15 million.

Three conditions apply. The purchased shares must be acquired directly from the company, not from another holder. The company must pass the gross assets test at that later issuance, measured immediately after the round closes and including the new cash. And each block runs its own holding period: gain on the Series B shares is eligible only once those shares have been held at least three years, and reaches 100% exclusion at five, independent of how long you have held the founder shares.¹⁵

Unlike the flat dollar cap, the 10x cap is not reduced by exclusions you took in earlier years. It is recomputed each year from the basis of the shares you sell that year, which makes the timing of each block’s sale a planning variable.¹⁶

Contributing Appreciated Property

You can also contribute appreciated property, such as intellectual property, in exchange for QSBS shares. This can increase your basis in the same way as a cash contribution.

The key caveat: pre-contribution built-in gain on that property is not sheltered by the Section 1202 exclusion. Your Section 1202 basis is set at no less than the property’s fair market value at contribution, so only appreciation after the property is inside the C corporation can qualify.¹⁷ The contributed property is also counted at fair market value for the gross assets test.¹⁸

This approach is more complex than a cash contribution. The strategy earns its complexity when the IP is still early and most of the value will be created inside the corporation. If the property is already highly appreciated, you are mostly converting non-excludable gain into a larger cap for gain that may never materialize.

These two terms get confused regularly. They describe different strategies with different mechanics.

A founder can use both strategies together. A donee takes the donor’s basis in gifted shares, so packed basis carries over and each recipient’s 10x cap is computed on it.¹⁹ Packing raises what a single taxpayer can exclude. Stacking then multiplies that across additional qualified holders. These are complementary approaches, not competing ones.

The OBBBA, signed into law on July 4, 2025, updated Section 1202 in three ways that directly affect packing strategy.

Higher flat dollar cap. The per-taxpayer exclusion cap increased from $10 million to $15 million for stock acquired after July 4, 2025. This raises the point at which packing becomes advantageous. Founders now need more than $1.5 million of basis in the shares sold that year before the 10x cap exceeds the $15 million floor. Note that the cap is cumulative per company: eligible gain already taken on earlier sales of that company’s stock, including pre-OBBBA shares, reduces the amount available.²⁰

Higher gross assets threshold. The gross assets limit increased from $50 million to $75 million for stock issued after July 4, 2025. This gives LLC-to-C-corp conversions more room at higher valuations before hitting the disqualification threshold.

Tiered holding periods. Stock acquired after July 4, 2025 qualifies for a 50% exclusion at three years, 75% at four, and 100% at five or more. Earlier stock still needs more than five years for any exclusion. Both the $15 million cap and the $75 million threshold are indexed for inflation beginning in 2027.²¹

The cap applies to stock acquired after July 4, 2025, and the gross assets limit to stock issued after that date. Earlier stock still follows the original $10 million flat cap and $50 million gross assets limit.

Section 1202 is a federal exclusion. Your state may not follow it. California does not conform and taxes the full gain at rates up to 13.3% regardless of how large your federal exclusion is. New York and New Jersey (for tax years beginning on or after January 1, 2026) conform. Oregon, Illinois, Vermont, and Maine have decoupled in whole or in part for 2026. Model packing against your state of residence at the time of sale, not just the federal cap.

QSBS packing is not the right move for every founder. It requires deliberate action well before any exit is on the table.

Packing tends to make the most sense when:

• Your expected exit value significantly exceeds $15 million per taxpayer
• You have capital available to contribute at original issuance
• You have enough runway for the QSBS clock to run on the newly issued shares: three years for a 50% exclusion, four for 75%, and five or more for 100%
• Post-conversion or post-contribution growth is expected to substantially exceed the basis established

It tends to make less sense when:

• The exit price is uncertain or modest relative to the basis you would establish
• The LLC conversion valuation is high relative to the eventual exit price
• There is not enough time before the expected liquidity event for the QSBS clock to qualify

Once a term sheet is on the table, most structuring options are already gone. The right time to evaluate a packing strategy is years before any deal begins.

Work With a QSBS Specialist Before You Act

QSBS packing can expand your Section 1202 exclusion well beyond the flat dollar cap. The rules are precise, the downside scenarios are real, and every step has to happen before a deal is in motion.