QSBS stacking and packing: A founder’s exit strategy

This article explains two advanced tax strategies, QSBS stacking and packing, that can help you get the most from the financial benefits of the qualified small business stock gain exclusion at exit.

QSBS: An overview

The qualified small business stock (QSBS) exemption offers founders, early employees, and investors in certain companies the ability to exclude up to $15 million of capital gains (or 10x their basis, whichever is greater) at exit. QSBS stockholders can use two strategies—QSBS stacking and QSBS packing—to potentially reduce or even eliminate capital gains taxes altogether.

Note that not all stock qualifies for QSBS. Companies must meet several statutory requirements under the Internal Revenue Code (IRC), including having less than $75 million of gross assets at the time when shares are issued.

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What is QSBS stacking?

QSBS stacking is a tax planning strategy that multiplies the QSBS gain aggregate exclusion by gifting shares to other individuals or trusts before a sale. It is a way to legally increase the total amount of capital gains that can be shielded from taxes across your family, effectively managing your tax exposure, though not without risk. The strategy works because the exclusion limit applies on a per-taxpayer basis.

Think of your personal QSBS exclusion as one tax-free "bucket" for your capital gains. Once that bucket is full, any additional gains you realize will spill over and be subject to federal income tax. QSBS stacking allows you to create several additional empty buckets by transferring your stock to others, such as your children or specially designed trusts. Each new taxpayer who receives your gifted stock gets their own separate exclusion bucket, allowing your family to collectively shelter more of the total gain from taxes.

QSBS stacking (and packing) strategies are especially useful for startup founders and business owners planning for an eventual exit. Instead of raising one large, priced round, many founders opt for a more flexible approach. Using a SAFE (simple agreement for future equity) has become the primary strategy for founders raising seed capital, especially for those managing fundraising totals before a priced round. In fact, data from a one-year period ending in Q3 2024 shows that SAFEs are the most popular choice, accounting for 64% of all seed rounds, compared to just 27% for priced equity rounds and 10% for convertible notes.

This is where QSBS stacking comes in. Consider a founder who holds shares with a low cost basis and an unrealized gain of $25 million. If they were to sell these shares on their own, the QSBS exclusion limit would cap their tax-free gain at $15 million, leaving a significant portion of the gain subject to capital gains tax.

However, if the founder gifts a portion of their shares to a separate, irrevocable non-grantor trust for the benefit of their children, a separate taxpayer is created. This trust qualifies for its own QSBS gain exclusion. For instance, if the founder gifts shares with a potential gain of $12.5 million to the trust and keeps the same amount for themselves, both the founder and the trust can each claim $15 million under the new rules exclusion. This strategy increases the total tax-free gain.

How to use gifts and trusts for QSBS stacking

QSBS stacking is a powerful estate planning tool for business owners—transferring QSBS shares to irrevocable trusts can optimize wealth transfer and estate tax planning.

The tax code allows you to gift QSBS to others without the stock losing its qualified status, which is the core mechanism behind QSBS stacking. The person or entity that receives the gift also inherits your original holding period and cost basis; under the tax code, this transfer ensures the recipient is treated as having acquired and held the stock just as you did, allowing them to qualify for the exclusion when it's eventually sold.

The most common method for a stacking strategy is gifting QSBS shares to irrevocable non-grantor trusts, a different approach to equity distribution than methods like employee stock ownership plans (ESOP). The IRS recognizes a non-grantor trust as a separate and distinct taxpayer from the person who created it. Because it's a separate taxpayer, the trust qualifies for its own, separate QSBS gain exclusion.

Examples of potential recipients for a gift of QSBS, another advanced strategy alongside a Section 1045 rollover, include:

• Individual family members, such as children or parents

• A non-grantor trust established for the benefit of a child

• Multiple non-grantor trusts, with each one set up for a different beneficiary

Key risks and rules for QSBS stacking

While QSBS stacking is a powerful strategy, it is also a complex area of tax law with rules that must be followed carefully. As a founder, it's important to be aware of the potential pitfalls to ensure your planning is effective and can withstand scrutiny from the IRS. Being proactive and informed is the best way to protect yourself and your potential tax savings.

• The multiple trust rule: If you create multiple trusts for the same beneficiary with the primary purpose of tax avoidance, the IRS has the authority under Section 643(f) to collapse multiple trusts and treat them as a single entity for tax purposes. This would defeat the purpose of stacking, as you would only get one exclusion instead of many.

• The burden of proof: It is always the taxpayer's responsibility to prove that their stock qualifies as QSBS and that they have met all the necessary requirements. This can be incredibly challenging to do years after the stock was first issued if you don't have meticulous records.

• State tax conformity: While the federal government offers a complete tax exemption on QSBS gains, not all states follow these rules. This discrepancy creates a significant tax risk, particularly in states with major startup ecosystems. In California, for instance, where startups collected nearly half of all U.S. venture capital raised in 2024, a capital gain that is tax-free at the federal level is still subject to state income tax. Conversely, states like New York fully conform to the federal Section 1202 exclusion rules.

• The compliance multiplier risk: QSBS stacking multiplies your audit risk. Because each trust is a separate taxpayer, each must be able to prove that the company met the “substantially all” requirement for the duration of that specific trust's holding period. If the company fails the active business test for a two-year window, it could potentially disqualify the tax exclusion for every trust involved. Annual QSBS attestation is the only way to ensure that you have a contemporaneous record for every taxpayer in your stacking strategy, rather than trying to recreate financial history for five different trusts years after the fact.

Navigating these requirements can be daunting, but meticulous record-keeping is non-negotiable. To help you stay on the right side of the rules and protect your potential tax break, download our guide on QSBS eligibility.

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Understanding gift tax valuation

Transferring QSBS shares to trusts or individuals is a powerful way to maximize the exclusion benefit, but it’s also a moment that triggers potential gift tax liability. The IRS requires an auditable, defensible fair market value (FMV) for every gifted equity transaction, not just for QSBS but within broader estate and gift tax rules. An accurate FMV is critical for setting the value of the gift, minimizing consumption of your lifetime gift tax exemption, and preventing future audits or penalties.

The ideal moment for a valuation is just before you execute any QSBS gift or transfer, especially early, when company valuation remains low and you aim to conserve as much of your lifetime gift exemption as possible. Working with Carta helps ensure the FMV stands up to future audits, supporting IRS safe harbor status and minimizing costly surprises at exit.

Pros and cons of non-grantor trusts

Using non-grantor trusts for QSBS stacking is a powerful strategy, but it comes with both advantages and disadvantages that should be carefully considered.

Pros:

• Separate taxpayer status: The most significant benefit is that a non-grantor trust is a separate tax entity, allowing it to claim its own QSBS gain exclusion. This can multiply the potential tax-free gain.

• Estate planning: Assets transferred to an irrevocable trust are typically removed from the founder's taxable estate. This can help reduce future estate tax liability and facilitate wealth transfer to heirs.

• Asset protection: Trusts can offer protection from creditors and legal claims, safeguarding the gifted QSBS shares.

Cons:

• Gift tax implications: Gifting shares to a trust may use a portion of the founder's lifetime gift tax exemption. This is why it's crucial to make the gifts when the company's valuation is still low to use as little of this exemption as possible.

• Loss of control: The founder must relinquish control and access to the gifted shares. Once assets are in an irrevocable trust, they generally cannot be returned to the founder.

• Compressed tax brackets: While trusts can save on capital gains, they face highly compressed income tax brackets. They reach the highest federal tax rate on a much lower amount of income compared to an individual, which could be a concern for trusts that retain significant income.

• Administrative complexity: Trusts require separate tax filings, and their administration can be more complex and costly than simply holding the shares in one's name.

What is QSBS packing?

While stacking focuses on multiplying the number of taxpayers, QSBS packing is a strategy that focuses on maximizing the annual exclusion limit for a single taxpayer. It works by intentionally increasing the cost basis of your stock.

This approach shifts the calculation in your favor. By increasing your cost basis, you also increase the potential size of your 10x basis annual exclusion. If your potential gain is so large that even a stacking strategy isn't enough to cover it, packing can become a more powerful tool for tax planning.

How to increase your basis with entity conversions and high-basis stock

There are two primary methods for executing a packing strategy. Both involve making strategic decisions long before an exit event, such as an M&A transaction.

• LLC to C corp conversion: Starting your business as a pass-through entity like a limited liability company (LLC) and later converting to a C corporation can establish a higher initial basis for your stock. The FMV of the business at the moment of conversion becomes the new cost basis, effectively "packing" that value into the shares from day one as a corporation.

• High-basis stock sales: If you sell private company stocks with a high basis in the same calendar year as your low-basis founder shares, you add the basis of all shares sold together for the 10x calculation. This high-basis stock might have been acquired in a later priced round or through other means, and selling it alongside your founder stock can significantly increase your annual exclusion limit.

The QSBS packing process

Carta recommends working with a legal and tax advisor to ensure compliance. In order to implement QSBS packing, follow these basic steps:

1. Evaluate eligibility: Before the company reaches a certain size or value, determine if it qualifies as a QSBS under IRS guidelines. The business must meet the requirements at the time of stock issuance.

2. Convert your entity: An LLC can be converted into a C corporation, a necessary step for the company's stock to qualify for QSBS treatment. Stock issued after the conversion may be eligible for the tax exemption, provided all other QSBS requirements are met.

3. Be mindful of timing: To be eligible for QSBS exemption, the eligible stock must be held for at least five years after conversion.

When should you start your QSBS planning?

QSBS stacking and packing are not last-minute tactics you can apply right before a sale or initial public offering (IPO). They are long-term exit strategies that depend on decisions made years in advance, often at the earliest stages of your company's life.

The choice of your business entity, for example, happens during the "Seed & Setup" phase of the founder journey. The ideal time to gift stock to trusts for a stacking strategy is during the early growth phase, when you are also building out your team's compensation structure and the company's valuation is still low, which helps minimize any potential gift tax consequences. The common thread through all these stages is the need for meticulous, auditable records of every equity transaction, ensuring stock is tracked from its original issuance—a key component of accounting for equity and a process simplified by equity management software.

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State tax considerations for QSBS

The QSBS exclusion is a federal tax benefit. The rules for state income tax can be very different, and this is a critical piece of practical advice for any founder or investor planning an exit.

Some states with high income tax rates do not conform to the federal QSBS rule. For example, California does not conform to federal QSBS rules, so business owners may still owe a substantial amount in state capital gains tax. You should always consult with a tax professional about the rules in your state of residence and the states where your company operates.

Why annual attestation is the gold standard for stacking

Because QSBS eligibility can be lost if requirements are not met for “substantially all” of a shareholder’s holding period, it’s not enough to confirm status once at the time of a gift or an exit.

As a best practice, companies should complete a QSBS eligibility review and refresh their attestation letter at least once per year, and after major events like large financings, stock repurchases, or business model changes. For those utilizing a stacking strategy, these annual letters create a year‑by‑year record that protects every trust and individual recipient. 

Carta’s QSBS attestation service automatically performs this review every 12 months, tagging eligible securities and providing updated company‑ and shareholder‑level letters to support ongoing compliance for you and your beneficiaries.

How Carta helps you stay compliant and exit-ready

Whether it’s tax season or you’re preparing for liquidity, as a founder, one of your biggest fears might be that a simple record-keeping error could jeopardize millions of dollars in savings. To successfully claim the QSBS exclusion, you should maintain a robust and thorough file of corporate records spanning from the date of incorporation through your entire holding period. The burden of proof rests with the taxpayer, and these records are essential for substantiating that all key requirements have been consistently met.

Carta's cap table management platform acts as the single source of truth for your company's equity, replacing messy spreadsheets that are prone to costly mistakes. Using disconnected spreadsheets for your cap table and waterfall models slows deals and adds risk during critical moments like fundraising. Carta provides the clean, auditable records of every stock issuance, transfer, and 409A valuation that are required to prove compliance with standards like Accounting Standards Codification 718 (ASC 718).

Carta also offers a QSBS Attestation service directly on our platform. Carta integrates this service, providing an efficient and reliable way to get the documentation you may need for tax filing and to comply with new regulations.

To see how Carta can help you prepare for a successful exit, speak to an expert.

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Frequently asked questions about QSBS stacking and packing

What is the 80% active business requirement?

For stock to qualify as QSBS, the company must use at least 80% of its assets in the active conduct of a qualified trade or business for substantially all of the shareholder's holding period, which often begins after stock vesting.

Can my spouse and I both claim the QSBS tax exemption?

For QSBS acquired on or after July 5, 2025, the per-taxpayer exclusion cap has increased to the greater of $15 million (indexed for inflation after 2026) or 10 times the adjusted basis. A key provision of this updated law clarifies that for a married couple filing separate returns, this gain exclusion cap is split equally between the spouses, meaning each spouse has a separate $7.5 million exclusion, for a potential combined total of $15 million per company.

What is the difference between a grantor and non-grantor trust?

A grantor trust is tied to its creator for tax purposes and does not create a new exemption, while a non-grantor trust is a separate taxpayer (much like a special purpose vehicle (SPV)) and therefore qualifies for its own QSBS gain exclusion.