IDGT Estate Planning: How Intentionally Defective Grantor Trusts Work

For families with significant wealth, successful estate planning often comes down to a deceptively simple objective: move future appreciation out of the taxable estate without unnecessarily giving up control, flexibility, or access to capital today.

An Intentionally Defective Grantor Trust, commonly known as an IDGT, is one strategy that can accomplish exactly that. Despite its peculiar name, an IDGT is not defective because something went wrong. The “defect” is intentional. The trust is deliberately structured to be treated differently under two separate parts of the tax code.

For estate and gift tax purposes, assets transferred to a properly structured IDGT can generally be removed from the grantor’s taxable estate. For income tax purposes, however, the grantor continues to be treated as the owner of the trust. That mismatch can create a powerful estate-planning opportunity for high-net-worth and ultra-high-net-worth families, particularly when the trust owns assets expected to appreciate substantially.

What Is an Intentionally Defective Grantor Trust?

An Intentionally Defective Grantor Trust is an irrevocable trust designed to remove assets from the grantor's estate while continuing to treat the grantor as the owner of those assets for federal income tax purposes.

The terminology can be confusing because an IDGT is “defective” only from the perspective of the income-tax rules. The trust is generally intended to be effective for estate-planning purposes. Once a completed gift is made to the trust, the transferred property and subsequent appreciation may be outside the grantor's taxable estate, assuming the trust has been properly drafted and administered.

At the same time, one or more provisions of the trust cause the grantor to remain the owner for federal income-tax purposes under the grantor-trust rules of Internal Revenue Code Sections 671 through 679. The IRS describes a grantor trust as one in which another person, generally the grantor, is treated as owning some or all of the trust's assets for income-tax purposes. This dual treatment is what gives the IDGT much of its planning power.

Why Would Someone Intentionally Create a “Defective” Trust?

The primary goal of an IDGT is generally to transfer appreciating assets to future generations while limiting the amount of future appreciation remaining in the grantor's taxable estate.

Consider a business owner with an interest currently valued at $10 million. If that interest grows to $30 million over the next 15 years and remains in the owner's estate, the entire $30 million may ultimately be subject to estate tax, depending on the owner's remaining exemption and estate-planning circumstances. If the $10 million interest is instead transferred to a properly structured IDGT, the subsequent $20 million of appreciation may occur outside the grantor's estate.

For wealthy families, removing future appreciation can be every bit as important as transferring today’s assets. That distinction is fundamental. Effective estate planning focuses not only on the amount of wealth that can be transferred today, but also on identifying the assets most likely to create significant future estate tax exposure if they continue to appreciate within the taxable estate. Those assets are often the strongest candidates for advanced gifting and wealth-transfer strategies.

How Does an IDGT Work?

An IDGT generally begins with the creation of an irrevocable trust for children, grandchildren, or other beneficiaries. The grantor then transfers assets to the trust, either through an outright gift, a sale, or a combination of the two. The trust agreement deliberately includes provisions that cause the trust to be classified as a grantor trust for income-tax purposes, without necessarily including the trust assets in the grantor's estate.

One commonly discussed provision is a power of substitution, sometimes called a swap power. Under IRC Section 675, certain administrative powers can cause grantor-trust treatment. One such provision permits the grantor, when appropriately structured, to reacquire trust property by substituting other property of equivalent value. The exact drafting matters enormously. An estate-planning attorney must ensure that the provision creates the desired income-tax result without creating unwanted estate-tax inclusion.

The IDGT's Most Powerful Feature: The Grantor Pays the Income Tax

Because the grantor is treated as the owner of an IDGT for income-tax purposes, the grantor generally reports the trust's taxable income on the grantor's individual income-tax return. At first glance, that may sound like a disadvantage. For affluent families, it can be one of the strategy's greatest benefits.

Suppose an IDGT owns an investment portfolio producing $500,000 of taxable income. The grantor may personally pay the federal and potentially state income taxes attributable to that income while the $500,000 remains in the trust. Economically, the grantor is reducing his or her own taxable estate while allowing the trust assets to remain invested for the beneficiaries.

Even better, the IRS has ruled that when the grantor is legally responsible for the tax attributable to a grantor trust, the grantor's payment of that income tax is not itself treated as an additional taxable gift to the trust beneficiaries. This can result in an additional wealth transfer each year without requiring the grantor to make another conventional gift. For sufficiently large trusts over long periods, this “tax burn” can become an important part of the estate-planning strategy.

Using an Installment Sale to an IDGT

One of the most sophisticated IDGT strategies involves selling appreciating property to the trust in exchange for a promissory note. Rather than gifting the entire asset to the trust and using a large portion of the gift and estate tax exemption, the grantor may first make a smaller seed gift to the trust and subsequently sell additional assets to it.

For example: A business owner has a closely held business interest worth $10 million. The owner establishes an IDGT and contributes sufficient seed capital. The owner then sells the $10 million business interest to the IDGT. In exchange, the trust gives the owner a $10 million promissory note carrying an appropriate interest rate. The trust pays principal and interest on the note over time. What happens economically? The $10 million value of the asset has effectively been “frozen” in the grantor's estate as the note.

If the business interest subsequently becomes worth $25 million, the additional $15 million of appreciation can potentially accrue inside the trust rather than inside the grantor's estate. The strategy works best when the growth of the transferred asset exceeds the cost of financing the installment note.

The IDGT Freeze: How Future Growth Escapes the Estate

A visual look at how an installment sale can lock in today's value while shifting tomorrow's appreciation outside the taxable estate.

Does the Sale to an IDGT Trigger Capital Gains Tax?

Generally, a properly structured sale between a grantor and the grantor's IDGT is disregarded for federal income-tax purposes while grantor-trust status continues. The reasoning is unusual but important. For income-tax purposes, the grantor is treated as owning the trust assets. A transaction between the grantor and the grantor trust is therefore effectively treated as a transaction between the grantor and himself or herself.

Revenue Ruling 85-13 is foundational authority for this treatment. The IRS concluded in that ruling that because the grantor was treated as the owner of the trust, an exchange between the grantor and the trust did not constitute a recognized sale for federal income-tax purposes.

This means that a properly structured installment sale to an IDGT can potentially transfer a highly appreciated asset without immediately triggering the capital gain that an ordinary sale to an unrelated buyer might create. That is an exceptionally important distinction.

What Assets Work Well in an IDGT?

IDGTs tend to be most powerful when funded with assets that have substantial expected appreciation.

Possible candidates include:

• Interests in closely held businesses
• Pre-IPO or founder stock
• Concentrated equity positions
• Family limited partnership interests
• LLC interests
• Certain investment portfolios
• Income-producing real estate
• Development property
• Private equity interests
• Other assets expected to appreciate substantially

An asset generating strong cash flow may be particularly useful in an installment-sale strategy because the trust needs liquidity to service its promissory note. Asset selection should not be based solely on expected return, however. Income-tax basis, valuation, liquidity, cash flow, concentration risk, control rights, and the family's overall estate plan all matter.

IDGTs and the 2026 Estate Tax Exemption

The federal basic exclusion amount is $15 million per individual for 2026. That means some families who previously expected to face an immediate federal estate tax problem may now have additional room for planning. But a larger exemption does not make estate planning irrelevant. A family worth $20 million today could be worth considerably more 15 or 20 years from now.

Likewise, someone with a rapidly growing business, concentrated stock position, private-company equity, or appreciating real estate may eventually accumulate an estate well beyond the available exemption.

An IDGT can therefore be viewed not merely as a way to transfer existing wealth, but as a way to redirect future growth before it occurs. That is often where the greatest leverage exists.

The Basis Problem: Estate Tax Savings Can Come at a Cost

There is an important counterweight to the estate-tax benefits of an IDGT. Assets successfully removed from the grantor's taxable estate generally do not automatically receive a new income-tax basis equal to their fair market value upon the grantor’s death.

The IRS addressed this directly in Revenue Ruling 2023-2. It concluded that property held in an irrevocable grantor trust that is not included in the grantor's gross estate does not receive a basis adjustment under IRC Section 1014 merely because the grantor was treated as the trust's owner for income-tax purposes.

This creates one of the central trade-offs in advanced estate planning: Is it more valuable to remove the asset from the estate, or to retain it and potentially receive a step-up in basis at death? The answer depends on the numbers.

The Central Trade-Off: Estate Tax Savings vs. a Basis Step-Up

Removing an asset from the estate and keeping it for a step-up in basis both have real value — the right answer depends on the numbers.

For a family clearly exposed to substantial estate tax, removing decades of future appreciation may dramatically outweigh the potential capital-gains benefit of a basis adjustment. For someone with little or no likely estate-tax exposure, giving away a highly appreciated, low-basis asset could potentially create unnecessary future capital-gains taxes. This is why IDGT planning should integrate estate-tax planning and income-tax planning, rather than treating them as separate exercises.

Using a Swap Power for Basis Management

The grantor's power to substitute assets of equivalent value can potentially provide another planning opportunity. Imagine an IDGT owns stock worth $5 million with a basis of only $500,000. The grantor personally owns $5 million of cash or securities with very little embedded gain. Subject to the trust terms and applicable law, the grantor may potentially substitute $5 million of high-basis assets for the $5 million of low-basis stock held by the trust. The low-basis stock would return to the grantor.

If that stock is later included in the grantor's taxable estate, it may potentially qualify for a basis adjustment under Section 1014 at death. The trust would instead hold the high-basis assets. This type of planning illustrates why an IDGT should not simply be established and forgotten. The trust and the grantor's balance sheet should be reviewed periodically as asset values, tax basis, tax laws, health, family circumstances, and estate-tax exposure change.

What Happens to an IDGT When the Grantor Dies?

An IDGT does not necessarily terminate upon the grantor's death. Instead, the grantor-trust status attributable to the deceased grantor generally ends. The trust may then continue as a separate nongrantor trust for children, grandchildren, or future generations depending upon its governing document. The income-tax consequences of terminating grantor-trust status can be complex, particularly when outstanding debts, installment obligations, partnerships, or other sophisticated assets are involved. The trust's post-death administration should therefore be coordinated among the estate-planning attorney, tax professional, trustee, and financial advisor.

IDGT vs. GRAT: What's the Difference?

Both IDGTs and Grantor Retained Annuity Trusts can be used to transfer future appreciation, but their mechanics differ. A GRAT involves transferring assets to a trust while the grantor retains a specified annuity interest for a defined period. An IDGT installment-sale strategy generally involves transferring assets to a trust in exchange for a promissory note.

GRATs can be attractive when the grantor wants to transfer appreciation above the applicable Section 7520 hurdle rate while using little taxable gift exemption. IDGTs can offer greater long-term flexibility and can be particularly attractive when the objective is to establish a multigenerational trust and transfer substantial appreciating assets. Neither strategy is inherently better. They solve different planning problems.

IDGT vs. SLAT: What's the Difference?

A Spousal Lifetime Access Trust, or SLAT, is generally designed to remove assets from one spouse's estate while permitting the other spouse to remain a beneficiary of the trust. An IDGT describes the trust's income-tax treatment rather than its beneficiaries. In fact, a SLAT can itself be structured as a grantor trust. This means the two concepts are not mutually exclusive. A trust might simultaneously be:

• irrevocable,
• outside the grantor's taxable estate,
• a grantor trust for income-tax purposes, and
• a SLAT because the grantor's spouse is a beneficiary.

The terminology describes different characteristics of the same trust structure.

What Are the Risks of an IDGT?

IDGTs can be extraordinarily useful, but they are not appropriate for everyone. Important considerations include:

• Loss of direct ownership. Assets transferred through completed gifts generally belong to the trust, not the grantor.
• Gift tax exemption usage. Seed gifts and other transfers may consume available lifetime exemption.
• Valuation risk. Closely held businesses, real estate, LLC interests, and similar assets may require qualified appraisals.
• Liquidity. An installment-sale strategy requires the trust to make note payments.
• Income-tax burden. The grantor may face significant income taxes attributable to trust assets.
• Basis considerations. Assets outside the estate may miss a valuable basis adjustment at death.
• Administrative complexity. Trust accounting, tax reporting, valuations, note payments, and legal administration must be handled correctly.
• Changing tax laws. Estate, gift, GST, and income-tax laws can change over the many decades an irrevocable trust may exist.

An IDGT should therefore be implemented as part of a coordinated estate and financial plan, not as an isolated tax transaction.

Estate Planning Is About More Than Today's Estate Value

One of the biggest mistakes families can make is evaluating estate-tax exposure based solely on current net worth. A $15 million or $20 million estate today can become dramatically larger over the next several decades. A closely held business can multiply in value. Private-company equity can experience a liquidity event. Real estate can appreciate. Investment portfolios can compound.

An Intentionally Defective Grantor Trust can provide a powerful way to move some of that future growth outside the taxable estate before it occurs. But the most effective IDGT planning goes well beyond simply transferring assets.

A thoughtful strategy should account for the grantor’s remaining exemption, projected estate growth, income-tax basis, expected returns, valuation opportunities, liquidity needs, cash flow, potential capital-gains exposure, generation-skipping planning, and the family’s long-term objectives. The goal is to identify the right assets, transfer them at the right time, and structure the transaction so that the potential estate-tax benefits meaningfully outweigh the income-tax, administrative, and planning trade-offs.

For high-net-worth families, an IDGT can become an important part of a broader wealth-transfer strategy, particularly when significant appreciation is expected. When coordinated carefully with the family’s estate plan, tax strategy, and investment planning, it can help preserve more wealth for future generations while providing greater control over how and when that wealth is transferred.

Frequently Asked Questions About Intentionally Defective Grantor Trusts