The IRS has made it clear: QSBS stacking is in its crosshairs, and taxpayers who’ve built structures around multiplying their Section 1202 exclusion could soon find those arrangements unwound.
On May 20, 2026, Kenneth Kies — Treasury’s assistant secretary for tax policy — didn’t mince words at a Washington conference. “Let me just warn you, we don’t like stacking,” he said. Guidance is coming. The only questions are how far it reaches and whether it looks back.
What QSBS Stacking Actually Is
Section 1202 of the tax code lets non-corporate taxpayers exclude a significant chunk of gain when they sell qualified small business stock — provided they hold it long enough and meet a long list of other requirements.
The exclusion is capped on a per-taxpayer, per-issuer basis. That’s the key phrase. Because it applies individually, founders and investors have used gifting strategies — transferring shares to family members, non-grantor trusts, or incomplete gift non-grantor trusts (INGs) — so that each recipient can claim their own separate exclusion.
Stack enough taxpayers, and a single founder’s exit can generate tens of millions in tax-free gains that would otherwise be capped.
The IRC doesn’t explicitly ban this. Section 1202(h) actually confirms that QSBS retains both its qualified status and holding period when transferred by gift. That’s the legal opening stacking relies on.
Why the IRS Is Moving Now
Timing matters here. The One Big Beautiful Bill Act, signed July 4, 2025, raised the per-taxpayer exclusion cap from $10 million to $15 million for stock issued after that date — a 50% increase. It also introduced inflation indexing starting in 2027 and a tiered holding period structure that no longer requires a full five years to see a benefit.
That last point is a meaningful shift. Under the new tiered rules, investors holding post-OBBBA stock for just three years qualify for a 50% exclusion, four years gets them 75%, and the full 100% exclusion still kicks in at five. Previously, a founder who sold even a day short of five years walked away with nothing. Now there’s a graduated benefit throughout.
The bigger cap means every additional stacked taxpayer multiplies a larger number. A family trust structure that might have sheltered $30 million under old rules could shelter $45 million or more under the expanded regime. That’s the math the IRS is reacting to.
The Legal Hook Treasury Will Likely Use
The CBIZ article notes that guidance “could invoke” Section 643(f) — but the history here goes deeper than that framing suggests.
Treasury already tried this in 2018. Proposed regulations under §643(f) included a presumption that separate trusts had a tax-avoidance purpose whenever they generated a significant income tax benefit that couldn’t have been achieved with a single trust. That would have effectively shut down most QSBS stacking through multiple non-grantor trusts.
The presumption was dropped from the final regulations.
So the statutory hook exists, a prior attempt was made and pulled back, and now Treasury is signalling another run at it — with the added urgency of a larger prize and broader use of the strategy. Expect the 2018 draft to be the template for whatever comes next.
The question practitioners are wrestling with now is retroactivity. Transactions completed before new guidance is issued may survive if Treasury only applies the rules prospectively. But the IRS could take the position that stacking has always been prohibited under existing code provisions or judicial doctrines — meaning prior structures aren’t automatically safe just because they were set up before the announcement.
The State Tax Problem Nobody Is Talking About
Here’s a gap in most coverage of qualified small business stock: the federal exclusion and your actual tax bill are not the same thing.
Several states don’t conform to Section 1202 at all. California, Alabama, Mississippi, and Pennsylvania tax QSBS gains at full state income tax rates regardless of what the federal return shows. In California, that’s up to 13.3% on gains that are completely tax-free federally. On a $15 million exclusion, that’s roughly a $2 million state bill.
The landscape is also shifting in real time. New Jersey came into conformity with Section 1202 effective January 1, 2026 — a meaningful win for founders in that state. Oregon moved the opposite direction, decoupling from the federal exclusion in 2026 after estimating that automatic conformity with the OBBBA expansion would cost the state $888 million over two years.
For anyone planning QSBS structures — stacking or otherwise — state tax exposure can erode a substantial portion of the federal benefit. Trust siting in no-income-tax jurisdictions like Nevada, Delaware, or Wyoming is increasingly part of these conversations, particularly for California-based founders who can’t easily change their own residency before a liquidity event.
What This Means in Practice
Anyone currently holding QSBS and considering transfers to trusts or family members to multiply their Section 1202 exclusion should treat the current environment as materially more risky than it was twelve months ago.
That doesn’t mean stacking is dead. No regulation has been issued. The strategy remains technically available under current law. But completing structures before guidance lands is no guarantee of safety, particularly if Treasury signals that it views the practice as always having been improper.
A few things worth keeping in mind:
The IRS has form here. The 2018 proposed §643(f) regulations show this isn’t a new concern — it’s a revived one, with more political momentum behind it.
Pre-OBBBA and post-OBBBA stock aren’t treated the same. Structures built around the old $10 million cap carry a different risk profile than new planning designed around the $15 million cap. Treasury’s focus is almost certainly on the latter.
The non-grantor trust question remains unsettled. How many trusts are too many has never been given a clear answer. That ambiguity cuts both ways right now.
The bottom line is that QSBS stacking — and Section 1202 planning more broadly — just became significantly more complex. Anyone with meaningful QSBS exposure should be in conversation with a tax adviser now, not after the guidance drops.
This article is for informational purposes only and does not constitute tax or legal advice. Consult a qualified tax professional before taking any action based on your specific circumstances.
Sources: CBIZ · The Startup Law Blog · RSM · Davis Wright Tremaine · DarrowEverett · Tax Law Center · Lexology · Oregon SB 1507
