An intentionally defective grantor trust, or IDGT, is an irrevocable trust drafted so that the grantor is treated as the owner of the trust’s assets for income tax purposes but not for estate tax purposes. That split is the whole point. The grantor keeps paying income tax on what the trust earns, which lets the trust’s assets compound without being drained by tax bills, while the assets themselves sit outside the grantor’s taxable estate. For families with wealth above the federal exemption, that combination can move substantial appreciation to the next generation with no estate tax, no gift tax on the growth, and no capital gains tax on the transfer itself.
Two Tax Systems, One Trust
Federal law does not treat trusts the same way under the income tax rules and the estate tax rules. An IDGT is engineered to exploit that gap on purpose. Under the grantor trust rules beginning at Internal Revenue Code Section 671, when the grantor retains certain powers over a trust, the IRS treats the grantor as the owner of the trust’s assets for income tax. Interest, dividends, capital gains, and other trust income all land on the grantor’s personal return.1Office of the Law Revision Counsel. 26 USC 671 – Trust Income, Deductions, and Credits Attributable to Grantors and Others as Substantial Owners
The “defect” is where the advantage lives. Even though the grantor is taxed on the trust’s income, the assets are not part of the grantor’s taxable estate. The trust is irrevocable, and the grantor has given up ownership. Estate tax law respects the transfer. Income tax law ignores it. The mismatch is intentional because it produces a better outcome than either a conventional irrevocable trust or a fully taxable one.
What Makes the Trust “Defective”
The trust document has to include specific provisions that trigger grantor trust status. Those provisions are chosen so they create income tax ownership without dragging the assets back into the estate. Most planners rely on the administrative powers listed in IRC Section 675.
The most common trigger is the power to substitute assets. Under Section 675(4)(C), if the grantor holds the power to reacquire trust property by swapping in other property of equivalent value, the trust becomes a grantor trust for income tax.2Office of the Law Revision Counsel. 26 USC 675 – Administrative Powers The power must be exercisable in a nonfiduciary capacity without the trustee’s approval. In practice, the grantor might swap cash or publicly traded securities into the trust in exchange for a closely held business interest already inside it. As long as the values match, the swap moves no tax needle.
The selection of triggering powers requires precision. The wrong combination of retained powers can inadvertently cause estate tax inclusion under a different section of the code and defeat the entire strategy.
Moving Assets In: The Installment Sale
The typical IDGT transaction has two steps. First, the grantor makes an initial gift to the trust, often called a seed gift, to give it independent assets. A common practitioner convention is to seed the trust with assets equal to at least 10% of the eventual sale price, though that figure appears in no IRS ruling or court case. Its real purpose is to show the trust can service its future obligations. The seed gift uses part of the grantor’s lifetime gift and estate tax exemption.
Second, the grantor sells appreciating assets to the trust in exchange for a promissory note. This is the engine of the strategy. Because the IRS treats the grantor and the grantor trust as the same taxpayer for income purposes, the sale is a non-event for income tax. Under Revenue Ruling 85-13, a transaction between a grantor and their grantor trust cannot be recognized as a sale, because the same person is treated as owning the property on both sides. No capital gains tax is triggered, even if the assets have appreciated significantly.
For estate tax, the sale is entirely real. The assets leave the grantor’s estate and belong to the trust. What remains in the estate is the promissory note, at its fixed face value. If the assets in the trust grow faster than the interest rate on the note, everything above that rate passes to the beneficiaries free of estate tax.
The Note and the Applicable Federal Rate
The promissory note has to charge interest at least equal to the Applicable Federal Rate published monthly by the IRS. For mid-term notes with terms between three and nine years, the AFR as of March 2026 is 3.93% annually.3Internal Revenue Service. Revenue Ruling 2026-6 The key point: if the transferred assets return more than the AFR, everything above that rate effectively moves to the beneficiaries tax-free. At a rate under 4%, assets that appreciate at 8% or more can shift enormous value out of the estate over the life of the note.
Structuring matters. Interest payments cannot be tied to the income of the transferred asset, and a note that fails to look like a bona fide obligation invites the IRS to recharacterize the transaction and pull the assets back into the estate.
Why the Grantor Paying the Tax Is a Feature
The grantor’s obligation to pay income tax on the trust’s earnings is not just a quirk of the design. It is one of the most powerful features. Every dollar of tax the grantor pays is a dollar that stays inside the trust, compounding for the beneficiaries. Over fifteen or twenty years, this effect can outweigh the value of the original transfer.
Under Revenue Ruling 2004-64, the grantor’s payment of income tax on grantor trust income is not treated as an additional gift to the trust or its beneficiaries. It’s the grantor satisfying their own tax obligation. So a grantor can pay hundreds of thousands of dollars a year in taxes on trust income without any gift tax consequence, while each of those payments also shrinks their personal estate. It works as a second channel of estate reduction running alongside the appreciation shift.
The Estate Freeze in Numbers
Planners call the combined effect an estate freeze. At the moment of sale, the value in the grantor’s estate is locked at the note amount. All future appreciation belongs to the trust.
A simplified example makes it concrete. A grantor sells a $10 million business interest to an IDGT in exchange for a nine-year promissory note at 3.93% interest. If the business grows at 10% a year, after nine years it is worth roughly $23.7 million. The grantor’s estate holds a note that has been gradually repaid. The trust holds an asset worth about $13.7 million more than the original sale price. That $13.7 million passes to the beneficiaries with no estate tax, no gift tax on the growth, and no capital gains tax triggered by the sale.
The strategy works best with assets expected to appreciate substantially: closely held businesses, real estate in growing markets, concentrated stock positions. If the transferred assets don’t outperform the AFR, the IDGT delivers little benefit compared with just holding them.
What Can Go Wrong
IDGTs are powerful but not forgiving. Several failure modes are hard or impossible to fix later.
Death During the Note Term
If the grantor dies while the promissory note is still outstanding, the trust loses its grantor trust status. The installment sale that was invisible for income tax may suddenly generate consequences. The outstanding note balance is included in the grantor’s taxable estate, and deferred capital gains may come due on the unpaid portion. Planners sometimes address this with shorter note terms or by holding life insurance in a separate irrevocable life insurance trust to cover the potential tax hit.
Retained Control and Section 2036
If the grantor keeps too much control over the assets or continues to benefit from them personally, Section 2036 can pull the entire trust back into the taxable estate. That section applies when the grantor has retained the right to possess or enjoy the transferred property, receive its income, or decide who benefits from it.4Office of the Law Revision Counsel. 26 USC 2036 – Transfers With Retained Life Estate There is an exception for bona fide sales for adequate consideration, which is why the installment sale structure and clean note terms matter. If the IRS argues successfully that the sale wasn’t genuine, the estate freeze unravels.
Assets That Don’t Appreciate
The math only works when transferred assets outrun the note’s interest rate. If they decline or grow slowly, the grantor has given away property and taken on an income tax burden for little estate tax benefit. There is no clean way to reverse the sale after the fact.
Economic Substance Challenges
The IRS can challenge the deal for lacking economic substance if the trust looks unable to service the note from its own resources. A trust with nothing but the property purchased from the grantor, with payments funded by continuing gifts from the grantor, resembles a circular transaction rather than a real sale. The seed gift and careful note terms exist to address exactly that vulnerability.
Where the 2026 Exemption Leaves the Strategy
The federal estate and gift tax basic exclusion amount for 2026 is $15,000,000 per individual, or $30,000,000 for a married couple.5Internal Revenue Service. What’s New – Estate and Gift Tax That figure was set by the One Big Beautiful Bill Act, which made the higher exemption permanent and raised it slightly from 2025. The annual gift tax exclusion for 2026 is $19,000 per recipient.6Internal Revenue Service. Gifts and Inheritances
Even at $15 million, IDGTs remain relevant for anyone whose estate already exceeds that number or is expected to. The strategy is particularly attractive when asset values are temporarily depressed, when AFR rates are low, or when the grantor holds assets likely to appreciate rapidly. Final regulations also confirm that gifts made under a higher exclusion amount won’t be clawed back if the exclusion later decreases, which protects completed IDGT transactions from future legislative shifts.7Internal Revenue Service. Making Large Gifts Now Won’t Harm Estates After 2025
The layers of law here interact in non-obvious ways, and a structuring error can produce the opposite of the intended result. Anyone considering an IDGT should work with an estate planning attorney and a tax advisor with direct experience in grantor trust transactions.