- QSBS stacking and packing: Using estate planning to maximize benefits
- QSBS: An overview
- What is QSBS stacking?
- How to use gifts and trusts for QSBS stacking
- Key risks and rules for QSBS stacking
- Understanding gift tax valuation
- Pros and cons of non-grantor trusts
- What is QSBS packing?
- How to increase your basis with entity conversions and high-basis stock
- The QSBS packing process
- When should you start your QSBS planning?
- Why annual attestation is the gold standard for stacking
- How Carta helps you stay compliant and exit-ready
- Frequently asked questions about QSBS stacking and packing
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. Two strategies, QSBS stacking and QSBS packing, can reduce or eliminate capital gains taxes entirely.
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 shares are issued. Common stock and shares acquired by exercising stock options may both qualify, but the requirements must be satisfied at the time of acquisition.
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 of QSBS. Because the exclusion limit applies on a per-taxpayer basis, each recipient qualifies for their own separate exclusion, effectively managing your tax exposure. It is a way to legally increase the total amount of capital gains that can be shielded from taxes across your family, though not without risk.
Think of your personal QSBS exclusion as a tax-free bucket for your capital gains. Once that bucket is full, any additional gains are subject to federal income tax. By transferring your stock to others, such as your children or specially designed trusts, each new taxpayer gets their own separate exclusion bucket and your family can collectively shelter more of the total gain from taxes.
QSBS stacking is particularly useful for startup founders managing large unrealized gains across founder shares. Consider a founder who holds shares with a low cost basis and an unrealized gain of $25 million. Selling 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 shares with a potential gain of $12.5 million to a separate, irrevocable non-grantor trust for their children, that trust becomes a separate taxpayer with its own $15 million exclusion. Between the founder and the trust, the full $25 million can be sheltered.
How to use gifts and trusts for QSBS stacking
QSBS stacking is also an estate planning tool. Transferring QSBS shares to irrevocable trusts can reduce estate tax exposure and facilitate wealth transfer to heirs.
The tax code allows you to gift QSBS without the stock losing its qualified status. The transferor gives up all interest in the shares at the time of the gift. The transferee inherits the transferor’s original holding period and cost basis; under the tax code, this transfer treats them as having acquired and held the stock in exactly the same way, which allows them to qualify for the exclusion when the stock is eventually sold.
The most common approach for QSBS stacking is gifting shares to irrevocable non-grantor trusts. The IRS treats a non-grantor trust as a separate taxpayer, distinct from the person who created it, so it qualifies for its own QSBS gain exclusion.
Examples of potential recipients for a gift of QSBS 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
An incomplete non-grantor trust (ING), which may offer additional flexibility around gift tax exposure depending on how it is structured and the state in which it is formed
Key risks and rules for QSBS stacking
While QSBS stacking is a powerful strategy, it is also a complex area of tax law and the IRS scrutinizes these arrangements. Understanding the main pitfalls before you plan is the best way to protect yourself and your potential tax savings.
The multiple trust rule: If you create multiple trusts for the same primary 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. You would get one exclusion instead of many, defeating the purpose of stacking.
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. Reconstructing that history years later, without contemporaneous records, is difficult and risky.
State tax conformity: While the federal government offers a complete tax exemption on QSBS gains, not all states follow these rules. In California, which attracted more than half of all U.S. venture capital raised in 2024, QSBS gains are still subject to state income tax. New York fully conforms to the federal Section 1202 exclusion rules. Always check the rules in your state of residence and the states where your company operates before building your exit plan around this exclusion.
The compliance multiplier: QSBS stacking multiplies your audit risk. Because each trust is a separate taxpayer, each must 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 reliable way to have a contemporaneous, year-by-year record for every taxpayer in your stacking strategy, rather than reconstructing financial history for multiple trusts years after the fact.
Meticulous record-keeping is not optional here. To help you protect your potential tax break, download Carta’s guide on QSBS eligibility.
Understanding gift tax valuation
Transferring QSBS shares to trusts or individuals triggers a potential transfer tax liability. The IRS requires an auditable, defensible fair market value (FMV) for every gifted equity transaction. The FMV sets the value of the gift, determines how much of your lifetime gift tax exemption is consumed, and prevents future audits or penalties.
The right moment for a valuation is just before any QSBS gift or transfer, ideally early in the company’s life when its valuation is low. Working with Carta helps ensure the FMV stands up to future audits, supporting IRS safe harbor status and minimizing 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: A non-grantor trust is a separate tax entity eligible for its own QSBS gain exclusion. This is the primary mechanism that makes stacking work.
Estate planning: Assets transferred to an irrevocable trust are typically removed from the founder's taxable estate. That reduces estate tax liability and facilitates 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. Transferring early, when the company's valuation is low, minimizes that cost.
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 than individuals. For trusts retaining significant income, this can partially offset the capital gains benefit.
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?
Where QSBS stacking multiplies the number of taxpayers, QSBS packing focuses on maximizing the annual exclusion limit for a single taxpayer by intentionally increasing the cost basis of your stock.
A higher cost basis means 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 extend your total shelter significantly.
How to increase your basis with entity conversions and high-basis stock
Packing requires strategic decisions long before an exit event, such as an M&A transaction.
C corp conversion: Starting your business as a pass-through entity like a limited liability company (LLC) or an S corporation 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
Work with a legal and tax advisor before implementing a QSBS packing strategy. The basic steps are:
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.
Convert your entity: An LLC or S corporation 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.
Mind the holding period: To be eligible for the exemption, 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.
Entity choice happens at the seed and setup phase. The best time to gift stock for a stacking strategy is during the early growth phase, when the company's valuation is still low and any gift tax consequences are limited.Throughout every stage, what makes these strategies defensible is auditable records tracing each share from original issuance forward, a process that equity management software makes practical at scale.
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 using 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
Claiming the QSBS exclusion requires a complete, auditable record of your company's equity history from incorporation through your entire holding period. The burden of proof sits with the taxpayer, and gaps in that record can cost millions.
Carta's cap table management platform serves as the single source of truth for your company's equity and replaces messy spreadsheets that introduce error risk at the worst possible moments. Carta provides the clean, auditable records of every stock issuance, transfer, and 409A valuation that are required to prove compliance with standards like ASC 718.
Carta also offers a QSBS Attestation service directly on its 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.
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.
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 gain exclusion, while a non-grantor trust is a separate taxpayer and therefore qualifies for its own QSBS gain exclusion.
DISCLOSURE: This communication is on behalf of eShares, Inc. dba Carta, Inc. ("Carta"). This communication is for informational purposes only, and contains general information only. Carta is not, by means of this communication, rendering accounting, business, financial, investment, legal, tax, or other professional advice or services. This publication is not a substitute for such professional advice or services nor should it be used as a basis for any decision or action that may affect your business or interests. Before making any decision or taking any action that may affect your business or interests, you should consult a qualified professional advisor. This communication is not intended as a recommendation, offer or solicitation for the purchase or sale of any security. Carta does not assume any liability for reliance on the information provided herein. ©2026 Carta. All rights reserved. Reproduction prohibited.
