You understand QSBS basics. You know stacking multiplies your exclusion. But what does that actually look like in practice?
Let’s break down a QSBS stacking example with actual numbers, showing you exactly how much tax you could save (or lose) depending on how you structure your exit. Meet Sarah, a venture-backed tech founder facing an $80 million acquisition. Her QSBS planning decisions will determine whether she keeps an extra $14 million or hands it to the IRS.
Sarah’s Baseline Situation
| Detail | Amount/Status |
|---|---|
| Role | Co-founder & CEO, SaaS Company |
| Total Shares Owned | 8 million |
| Cost Basis | $0.01/share ($80,000 total) |
| Company Exit Value | $800 million |
| Sarah’s Portion | $80 million |
| Total Capital Gain | $79,920,000 |
| Stock Issue Date | August 15, 2020 |
| Holding Period | 5+ years (acquired 2020, selling after August 15th, 2025) |
| Stock Type | Pre-OBBBA (acquired at original issuance on or before July 4, 2025) |
| Applicable Exclusion Cap | $10 million per taxpayer (pre-OBBBA limit) |
| State Residency | California |
Scenario 1: No QSBS Stacking
Sarah’s Tax Calculation Without Stacking
| Tax Component | Calculation | Amount |
|---|---|---|
| Total Capital Gain | $79,920,000 | |
| QSBS Exclusion (Individual Cap) | ($10,000,000) | |
| Taxable Gain | $69,920,000 | |
| Federal Tax | ||
| Long-Term Capital Gains (20%) | $69,920,000 × 20% | $13,984,000 |
| Net Investment Income Tax (3.8%) | $69,920,000 × 3.8% | $2,656,960 |
| Total Federal Tax | $16,640,960 | |
| State Tax (California) | ||
| Taxable Gain (CA doesn’t conform) | $79,920,000 | |
| California Tax (13.3%) | $79,920,000 × 13.3% | $10,629,360 |
| TOTAL TAX BILL | $27,270,320 | |
| After-Tax Proceeds | $80M – $27.27M | $52,729,680 |
Sarah keeps 65.9% of her $80 million exit. She just wrote a check for over $27 million in taxes.
Sarah’s Stacking Strategy
Two years before any exit discussions began, Sarah implemented proper QSBS stacking:
The Structure
| Element | Details |
|---|---|
| Trusts Created | 3 separate non-grantor trusts (one per child) |
| Children’s Ages | 8, 10, and 12 years old |
| Trust Differentiation | Different trustees, varied distribution standards, distinct investment approaches |
| Documentation | Asset protection, education funding, wealth education, |
| Transfer Amount | 2 million shares to each trust (6 million total) |
| Sarah’s Retention | 2 million shares personally |
| Transfer Timing | 24 months before any M&A discussions (transferred in 2023, two years before 2025 exit discussions) |
| Compliance | Filed Form 709 gift tax returns with independent appraisals. Shares were valued very low at the time. |
Scenario 2: With QSBS Stacking
Per-Position Tax Breakdown
| Position | Shares | Exit Value | Cost Basis | Capital Gain | QSBS Exclusion | Taxable Gain | Federal Tax (23.8%) |
|---|---|---|---|---|---|---|---|
| Sarah (Personal) | 2M | $20M | $20,000 | $19,980,000 | $10,000,000 | $9,980,000 | $2,375,240 |
| Child 1 Trust | 2M | $20M | $20,000 | $19,980,000 | $10,000,000 | $9,980,000 | $2,375,240 |
| Child 2 Trust | 2M | $20M | $20,000 | $19,980,000 | $10,000,000 | $9,980,000 | $2,375,240 |
| Child 3 Trust | 2M | $20M | $20,000 | $19,980,000 | $10,000,000 | $9,980,000 | $2,375,240 |
| TOTALS | 8M | $80M | $80,000 | $79,920,000 | $40,000,000 | $39,920,000 | $9,500,960 |
The Comparison
| Metric | No Stacking | With Stacking | Difference |
|---|---|---|---|
| QSBS Exclusion Used | $10 million | $40 million | +$30 million |
| Federal Tax Paid | $16,640,960 | $9,500,960 | -$7,140,000 |
| Percentage Saved | Baseline | ≈43% less federal tax | $7.14M saved |
Sarah saved $7.14 million in federal taxes through proper QSBS stacking.
State Tax Planning: California vs. Nevada Trusts
California doesn’t conform to federal QSBS treatment, but trust situs planning can help.
State Tax Comparison
| Strategy | Sarah’s CA Tax | Trusts’ Tax | Total State Tax | Combined Tax (Fed + State) | Total Savings vs. Scenario 1 |
|---|---|---|---|---|---|
| All California Trusts | $2,660,000 | $7,980,000 | $10,640,000 | $20,140,960 | $7,129,360 |
| Nevada-Situs Trusts | $2,660,000 | *$0 | $2,660,000 | $12,160,960 | $15,109,360 |
* Illustrative, assumes trusts are non-CA resident under CA rules and have no CA-source income. Properly structured non-grantor trusts with no California trustees, no California noncontingent beneficiaries, and no California-source income may reduce or eliminate California tax on the trust’s share, but California trust residency and sourcing rules are complex and must be vetted with SALT counsel.
In this illustrative scenario, where the Nevada-situs non-grantor trusts are treated as non-California residents under California law and have no California-source income, Sarah could reduce the trusts’ California tax by up to $7.98 million on top of her $7.14 million in federal savings, for a combined total savings of $15.11 million. California trust taxation depends on multiple factors, including the residence of fiduciaries, the presence of California non-contingent beneficiaries, and whether the trust has California-source income. These rules are nuanced, fact-specific, and frequently litigated, and any trust-situs planning must be reviewed with experienced SALT counsel.
Note on Post-OBBBA Stock: This example uses QSBS acquired at original issuance in 2020, which is subject to the pre-OBBBA $10 million per-taxpayer, per-issuer cap (or 10× basis, if greater). For QSBS acquired after July 4, 2025, the One Big Beautiful Bill Act generally increases the flat per-taxpayer, per-issuer exclusion cap to $15 million (still subject to the alternative 10× basis limitation) and introduces tiered exclusions: 50% after 3 years, 75% after 4 years, and 100% after 5 years. This would increase Sarah’s total exclusion from $40 million to $60 million (4 positions × $15M each), resulting in even greater tax savings. See our QSBS compliance article for details on the new OBBBA rules.
Timing: Right vs. Wrong Approach
Timeline Comparison
| Timeline Event | Correct Approach | Wrong Approach |
|---|---|---|
| Trust Setup | August 2023 (no exit discussions) | October 2025 (after LOI received, and right before deal signed) |
| Share Transfer | August 2023 | End of October 2025 |
| First Buyer Contact | August 2025 (24 months later) | August 2025 |
| LOI Received | September 2025 | September 2025 |
| Definitive Agreement | November 2025 | November 2025 |
| IRS Risk | Lower (estate planning purpose; sale not yet practically certain) | High (assignment of income) |
| Strategy Outcome | Works (saves $7.14M federal + $7.98M state) | Could fail (saves $0) |
The 24-month gap between trust funding and exit discussions helps support the position that transfers were motivated by independent estate planning objectives and occurred before a sale was practically certain.
Common Stacking Mistakes and Their Costs
What Mistakes Cost You
| Mistake | What Happens | Sarah’s Cost |
|---|---|---|
| Identical Cookie-Cutter Trusts | IRS aggregates under Section 643(f), treats as one trust | May lose entire $7.14M federal + $7.98M state savings |
| Using Grantor Trusts | Trusts aren’t separate taxpayers; no additional exclusions | May lose entire $7.14M federal + $7.98M state savings |
| Skipping Gift Tax Returns | Statute of limitations never starts, decades of IRS exposure | Potential penalties + strategy collapse |
| Ignoring State Tax | Perfect federal plan with massive state tax bill | May lose $7.98M in state savings |
| Last-Minute Transfers | Assignment of income doctrine applies | May lose entire $7.14M federal + $7.98M state savings |
Use Our QSBS Calculator
Do you want to review your own QSBS stacking potential? We built a comprehensive QSBS calculator that includes the ability to model stacking. Visit our QSBS calculator page below to review possible QSBS scenarios.
The Bottom Line
Sarah’s $15.11 million in total tax savings ($7.14M federal + $7.98M state) resulted from understanding QSBS stacking mechanics, implementing proper compliance, and executing transfers years before exit discussions. This example uses pre-OBBBA stock with $10M caps; post-OBBBA stock would yield even greater savings with $15M caps.
The math is straightforward:
Pre-OBBBA stock (acquired at original issuance on or before July 4, 2025):
- Each properly structured non-grantor trust = separate $10 million exclusion
- Each $10 million exclusion = $2.38 million in federal tax savings (when fully utilized)
- Multiple trusts + advance planning + state planning = $7M to $15M+ in savings
Post-OBBBA stock (acquired at original issuance after July 4, 2025):
- Each properly structured non-grantor trust = separate $15 million exclusion
- Each $15 million exclusion = $3.57 million in federal tax savings (when fully utilized)
- Multiple trusts + advance planning + state planning = $10M to $20M+ in savings
For venture-backed tech founders building toward exits above $30 million, QSBS stacking can save your family $10 million, $15 million, or more. But execution requires precision: non-grantor trust drafting, Section 643(f) compliance, proper timing, gift tax reporting, state tax planning, and comprehensive documentation.
The question isn’t whether stacking works. The tables above prove it does. The question is whether you’re planning early enough and with the right team to execute effectively.
Want to see how QSBS stacking numbers work for your specific exit scenario?
Connect with our founder to model your potential tax savings and determine whether stacking makes sense for your situation.
Connect with Keystone to model your QSBS stacking scenario
Sources & References
The information and illustrative examples in this article are based on current federal tax law, Treasury regulations, IRS guidance, state tax authority publications, and widely cited professional commentary regarding Qualified Small Business Stock (QSBS), trust taxation, and capital gains planning. Key reference materials include:
- Internal Revenue Code §1202 – Qualified Small Business Stock exclusion framework
- Treasury Regulation §1.643(f)-1 – Aggregation of multiple trusts for income tax purposes
- IRS Topic No. 559 – Net Investment Income Tax (NIIT)
- California Franchise Tax Board (FTB) guidance on QSBS nonconformity and trust residency rules
- One Big Beautiful Bill Act of 2025 (H.R.1) – Expanded QSBS exclusion limits and holding period tiers
