QSBS, DAFs, and the Stack Most CPAs Never Build
- J.T. Hardcastle
- Jun 29
- 5 min read
Updated: Aug 10
If you own founder stock in a C corporation, there's a provision of the tax code that can erase the federal tax on millions of dollars of gain when you sell. It's called Qualified Small Business Stock, and on its own it's powerful. Layered with gifts, trusts, and a donor advised fund, it becomes something most owners — and a surprising number of their accountants — never fully assemble: a coordinated stack that multiplies the exclusion and then wipes out the tax on whatever's left over.
This is advanced planning, and it only works with the right entity, the right timing, and good counsel. But the payoff for getting it right is large enough that every C-corp owner approaching a sale should understand the pieces. Here's the stack.
QSBS, in plain terms
Section 1202 lets you exclude capital gain from the sale of qualifying small business stock. The 2026 rules, reshaped by the One Big Beautiful Bill Act, are more generous than the old ones. For stock acquired after July 4, 2025, there's now a tiered exclusion: 50% at a three-year hold, 75% at four years, and 100% at five years or more. The per-issuer cap rose from $10 million to $15 million, indexed for inflation, and the company's gross-asset ceiling went from $50 million to $75 million. (Stock acquired earlier generally keeps the old $10 million, five-year, 100% rules.) Gain above the cap that isn't excluded comes back at a 28% rate.
In short: hold qualifying stock long enough and up to $15 million of gain per shareholder can be entirely federal-tax-free.
The stacking move
Here's the part most people miss. That $15 million cap applies per taxpayer — and a properly structured non-grantor trust counts as its own taxpayer with its own exclusion. By gifting QSBS into one or more non-grantor trusts for your family before a sale, you can multiply the number of $15 million exclusions in play. One shareholder has a single $15 million exclusion. The same shareholder who has gifted shares into three non-grantor trusts can have four exclusions — $60 million of gain shielded instead of $15 million.
This is "stacking," and it has to be set up early, with real trusts and real gifts, long before a sale is certain — the same timing discipline a pre-sale gift requires. Done at the last minute, it fails.
Where charity and the DAF come in
Stacking handles the gain you can exclude. The DAF handles the gain you can't. Suppose, even after stacking, you're left with several million dollars of gain above your exclusions, facing that 28% rate. Give that slice of stock to a donor advised fund before the sale, and the fund sells it tax-free while you take a fair-market-value deduction. The tax you would have paid on the non-excluded gain becomes a charitable deduction instead.
One important caution on trusts: a charitable remainder trust is itself tax-exempt, which means the Section 1202 exclusion is wasted inside it — the trust pays no tax on the sale anyway. A CRT can still be a fine way to convert concentrated stock into a lifetime income stream with a charitable remainder, but don't put QSBS you could exclude personally into one and throw the exclusion away.
The QSBS-plus-charity stack only works if the trusts, gifts, and DAF contribution are sequenced correctly and early. A Clarity Call coordinated with your CPA and attorney is where the stack gets built right — 30 minutes with a Partner, no pitch.
Approaching a C-corp sale? Run your stack in the DAF Calculator and a Clarity Call.
Building the full stack
Put together, the stack has three layers. First, claim your personal $15 million exclusion on the qualifying stock you keep. Second, multiply that exclusion by gifting shares into non-grantor trusts for your family, well before the sale. Third, give the leftover, non-excluded slice — the part that would otherwise be taxed at 28% — to a donor advised fund before the deal closes, turning that tax into a deduction and a charitable gift.
A founder facing a large exit who runs only the first layer leaves enormous value unclaimed. The owner who builds all three keeps more for their family, shields more from tax, and funds years of giving, all from the same sale. It's the kind of coordinated move that's easiest to plan in the high-income year of a liquidity event.
A fair warning to close: this is genuinely technical territory, full of qualification rules, holding-period traps, and entity requirements, and it must be coordinated with a CPA and an attorney who know Section 1202 cold. The point here isn't to do it yourself. It's to know the stack exists, so you can ask for it before the window closes. Most owners never do — which is exactly why most of them overpay.
Why most advisors never build it
If the QSBS stack is this valuable, why is it so rarely assembled in full? Partly because it crosses professional boundaries. The full stack touches tax law, trust and estate law, charitable planning, and investment strategy at once, and most advisors specialize in one of those lanes. The CPA may know Section 1202 cold but not the charitable layer; the estate attorney may build the trusts but never raise the DAF; the investment advisor may see the whole picture but lack the technical depth to execute. The stack falls through the cracks between specialists who each do their part well.
It also requires unusual timing discipline. Stacking through non-grantor trusts has to happen long before a sale, while the stock is still well below the exclusion caps and a transaction is genuinely uncertain — exactly when an owner is least focused on exit planning. By the time a deal is on the table, the most powerful moves have often expired. The lesson for any C-corp owner is to raise these questions years early and to insist on coordination across your advisors rather than assuming someone is quarterbacking the whole strategy. Usually no one is. The owners who capture the full stack are the ones who treat it as a single coordinated plan, started early, with one person responsible for making the layers fit together — not a series of disconnected tactics each professional happens to mention in passing.
QSBS qualification and stacking are highly fact-specific and must be built with your tax and legal advisors. The conversations that move people from "interesting idea" to "actual decision" happen one-on-one — your stock, your structure, an honest read.
Book a Clarity Call — 30 minutes with a Partner. No pitch. No homework.
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