Intentionally Defective Grantor Trusts (IDGTs)

If you own an asset you expect to multiply—founder’s stock, a closely held operating company, pre-IPO shares, a portfolio of appreciating real estate—and your estate is over the exemption, a sale to an intentionally defective grantor trust (IDGT) is the most efficient wealth-transfer structure in this chapter. It moves the entire upside to your heirs, consumes a fraction of your exemption, and unlike a GRAT it can fund a perpetual dynasty trust. If you learn one structure here, learn this one.

The name is tax-lawyer humor and it obscures what is happening. The trust is “defective” only in the sense that it is deliberately drafted to fail the grantor trust rules of IRC §§671–679 for income tax purposes while succeeding completely for estate and gift tax purposes. Two parts of the Code, two different answers about the same trust. To the estate tax, the assets are gone—out of your estate, future appreciation and all. To the income tax, the trust does not exist; you and it are one taxpayer. Every advantage below falls out of that deliberate split, and it is engineered with a specific retained power, most often the power to reacquire trust assets by substituting property of equivalent value under IRC §675(4)(C), “Administrative powers”—the same swap power that later solves your basis problem (section “Optimizing for Basis in the High-Exemption Era”).

The split runs two engines at once:

The tax you pay is a gift you never report

Because the trust’s income is legally yours, you pay the income tax on earnings that economically belong to your children. Rev. Rul. 2004-64 confirms this is not a taxable gift. So every April you move cash out of your estate and into your heirs’ pockets—gift-tax-free, on top of the annual exclusion, and without touching your lifetime exemption. A trust earning $1.5 million a year, taxed at a combined 40%, transfers $600,000 annually with no Form 709 and no limit.

You can sell to it without a tax bill

Under Rev. Rul. 85-13 a transaction between you and your own grantor trust is ignored, because you cannot buy from yourself. Sell an asset with a $1 million basis and a $15 million value and you recognize zero gain. Better still, the interest the trust pays you on the purchase note is not taxable income to you either.

Sale to an IDGT: The Three Steps

1. Seed it with a real gift

The trust must own something before it can credibly buy anything. Sell to an empty trust and the IRS will characterize your “note” as a retained equity interest instead of debt, and pull the entire structure back into your estate under IRC §2036. The practitioner standard is to gift roughly 10% of the value you intend to sell, so the trust carries genuine equity at risk behind the note. This seed gift uses lifetime exemption—and it is the moment to allocate GST exemption, while the value is still small. Do that and the trust’s inclusion ratio is zero permanently, which is exactly why the sale to an IDGT, and not a GRAT, is the structure that feeds a dynasty trust (section “Dynasty Trusts”).

2. Sell the asset for a note

Sell the appreciating asset to the trust in exchange for a promissory note bearing interest at the Applicable Federal Rate (AFR)—the floor rate the IRS will respect, and far below what the asset should earn. Structure it interest-only with a balloon at maturity, so cash stays inside the trust compounding instead of flowing back to you. Your estate is now frozen: it holds a fixed-value note instead of a growing business.

3. Wait

Everything the asset earns above the AFR accumulates inside the trust, outside your estate, untaxed by the gift or estate tax, and growing free of income tax because you are paying that bill personally.

A Worked Example You own an operating company. An appraiser values a non-controlling, non-marketable block of LLC units at $15 million. You gift $1.5 million of units to a newly drafted IDGT—using $1.5 million of your lifetime exemption and allocating $1.5 million of GST exemption—then sell a further $15 million of units to the trust for a nine-year interest-only note at a 4.0% AFR, or $600,000 of interest a year. The company compounds at 12% and distributes enough cash to service the note.

The trust’s assets follow a simple recursion—grow at the asset’s rate $g$, then pay the fixed interest $\mathit{rN}$ on the note—so after $n$ years the value is

with $V_0$ the seed plus the purchased units, $N$ the note principal, $r$ the AFR, and $g$ the growth rate. Here $V_0=\$16.5\text{M}$, $N=\$15\text{M}$, $r=4\%$, $g=12\%$, $n=9$:

Repay the $15 million balloon and $21.9 million remains. Table 23.8 tracks the path.

Your heirs end up with $21.9 million, for $1.5 million of exemption. Roughly $20 million of value left your estate without a dollar of gift tax—about $8 million of estate tax avoided at the 40% rate. Your estate received $600,000 a year of interest plus $15 million of principal, all of it frozen at face value while the business quadrupled. And that ignores the second engine: nine years of income tax paid personally on the trust’s earnings is several million dollars more transferred without a gift tax return. Run the same asset through a two-year GRAT and you move a slice of the appreciation one generation; run it through an IDGT and you move nearly all of it, permanently, into a vehicle your great-grandchildren can still be using.

Valuation Discounts The $15 million appraisal above is doing quiet work. When you transfer FLP or LLC interests instead of the underlying assets, the interests are worth less than their pro rata share, because a limited partner cannot control operations or force a liquidation. Appraisers routinely apply combined minority-interest and lack-of-marketability discounts of 20% to 40%, and under Rev. Rul. 93-12—which revoked the IRS’s earlier family-attribution position in Rev. Rul. 81-253—each transferred block is valued on its own, so the discount survives even when your family collectively controls the entity. At a 30% discount the $15 million appraisal above represents $\$15\text{M}∕0.7\approx \$21.4$ million of underlying business value—so $6.4 million of real value moves without appearing in the gift-tax computation at all. Get a qualified, defensible appraisal and follow the entity formalities—the discount is the first thing an examiner attacks, and the IRC §2036 traps that dissolve it are covered with the family LLC (section “LLCs for Estate Planning”). See IRS Pub. 561, “Determining the Value of Donated Property”.

What Goes Wrong

The asset underperforms the note

If the business grows slower than the AFR, the trust slowly hands its equity back to you as interest and the strategy fails. Unlike a GRAT, you do not get your exemption back—the seed gift is spent. Use an IDGT when you have real conviction about the asset; use a GRAT when you do not.

You die during the note term

The unpaid note sits in your estate at face value, which is fine—that was the plan. What is unsettled is whether your death, by terminating grantor trust status, triggers gain on the outstanding note. There is no clean authority. Keep the term comfortably inside your life expectancy.

The tax bill becomes a burden

Paying tax on income you never receive is a feature while you are wealthy and a problem if your circumstances change. Good drafting gives the trustee discretion to reimburse you; Rev. Rul. 2004-64 blesses that, while a mandatory reimbursement clause pulls the trust assets back into your estate. Draft it in from day one. Chief Counsel Advice 202352018 (2023) concluded that adding a reimbursement clause later, by court modification with the beneficiaries’ consent, is a taxable gift from the beneficiaries to you—so the retrofit is expensive and the IRS is watching.

No step-up at death

Assets in the trust are outside your estate, so they never receive a basis adjustment under IRC §1014. On a low-basis founder’s stake this can cost your heirs more than the estate tax you avoided. This is precisely what the retained swap power is for: late in life, substitute cash or high-basis assets into the trust and pull the appreciated stock back into your estate (section “Optimizing for Basis in the High-Exemption Era”).