GST Trust: Exemption, Inclusion Ratio, and Compliance

A generation-skipping transfer trust, usually shortened to GST trust, is an irrevocable trust built to move wealth to your grandchildren or later descendants while sidestepping the transfer taxes that would otherwise apply at each generation. For 2026, each person can shelter up to $15 million from the GST tax by allocating their lifetime exemption to the trust, and a married couple can protect up to $30 million combined.¹ Whether the trust actually avoids the 40% GST tax comes down to a single number called the inclusion ratio. Get it to zero and the trust is exempt forever. Miss, and every distribution to a grandchild is taxed.

What the GST Tax Is and Who Counts as a Skip Person

The GST tax is a federal levy that sits on top of the ordinary gift or estate tax. Congress created it so that families could not simply leapfrog a generation to avoid the estate tax that would apply at each level. Write a check directly to a grandchild and the transfer is exposed to both the estate or gift tax and the GST tax, unless your exemption absorbs it.

The tax targets transfers to a “skip person,” meaning anyone assigned to a generation two or more levels below you.² Within a family, generations follow the family tree: your children are one generation below you, grandchildren are two. For someone unrelated, the IRS measures by age gap from your birth date. A person born more than 37½ years after you is one generation below, and each additional 25 years marks a new generation.³

Three events trigger the tax:⁴

A direct skip, which is an outright transfer to a skip person that is also subject to gift or estate tax.
A taxable termination, which happens when an interest in the trust ends (typically because the non-skip beneficiary dies) and afterward only skip persons hold interests.
A taxable distribution, which is any distribution of income or principal from the trust to a skip person that is not one of the other two events.

The rate you pay on any of these is the maximum federal estate tax rate (currently 40%) multiplied by the trust’s inclusion ratio.⁵ Inclusion ratio of zero, no tax. Inclusion ratio of one, full 40%. Anywhere in between produces a proportional rate.

One boundary worth knowing before you assume the tax applies: if your child (the grandchild’s parent) has already died at the time of the transfer, that grandchild moves up one generation and is treated as a non-skip person. Their descendants shift with them.³ The GST tax does not reach that transfer at all.

The GST Exemption and How to Allocate It

Your exemption is the main tool for eliminating the tax. For 2026, it matches the basic exclusion amount of $15 million per individual.⁶ That figure was made permanent by the One Big Beautiful Bill Act signed on July 4, 2025, which extended what had been scheduled to sunset at the end of 2025, with inflation adjustments continuing from 2027.¹ Spouses each get their own $15 million.

Applying exemption to specific property is called allocation, and once made it is irrevocable. Lifetime allocations go on Form 709, the gift tax return.⁷ Allocations at death go on Form 706, the estate tax return. Two timing rules do most of the work:

A timely allocation, filed on Form 709 by the return’s due date (generally April 15 of the year after the gift), applies against the property’s value on the date you made the transfer.⁸
A late allocation applies against the fair market value on the date you actually file. If the property appreciated in the meantime, you burn extra exemption to cover the same trust.⁹

Most of the planning value lives in that timing difference. Fund a trust with $5 million in stock and file a timely allocation, and the entire trust is locked in as exempt even if the assets later grow to $50 million. Miss the deadline, wait until the assets are worth $50 million, and you would need $50 million of exemption to reach the same result. You probably don’t have it.

Certain transfers to GST trusts trigger automatic allocation of your exemption unless you affirmatively opt out on Form 709.⁸ If you plan to use your exemption elsewhere, you have to describe the transfer on a timely return and state that you are opting out. Silence is not neutral.

No Portability Between Spouses

The estate tax exemption is portable: a surviving spouse can inherit any unused portion of the deceased spouse’s basic exclusion through an election on Form 706.¹⁰ The GST exemption has no equivalent. If the first spouse to die has not allocated their GST exemption, it is gone. For couples with combined estates near or above $15 million, deliberate allocation planning for both spouses is essential.

Watch the Estate Tax Inclusion Period

You cannot allocate GST exemption to property that would still be pulled back into your taxable estate if you died today. During any estate tax inclusion period (ETIP), allocation is deferred until the period closes.¹¹ This comes up most often with grantor retained annuity trusts and qualified personal residence trusts, where the grantor keeps an interest for a term of years. When the ETIP ends, the property is valued at that point for exemption purposes, not at the date of the original transfer.⁸ Appreciation during the ETIP costs you more exemption.

The Inclusion Ratio: The Number That Decides Everything

The inclusion ratio tells you what percentage of the trust is exposed to the GST tax. The formula:¹²

Inclusion Ratio = 1 − (GST Exemption Allocated ÷ Value of Property Transferred)

The fraction inside the parentheses is the “applicable fraction.” Allocate exemption equal to the full transfer value and the fraction is 1, the inclusion ratio is zero, and the trust is fully exempt. Allocate nothing and the inclusion ratio is 1, making every future GST event taxable at the full 40%. The applicable fraction is rounded to three decimal places, so even an inclusion ratio of 0.001 means the trust is not fully exempt.¹²

Two Worked Examples

Transfer $5 million in cash to a GST trust and allocate $5 million of exemption on a timely Form 709. Applicable fraction: $5,000,000 ÷ $5,000,000 = 1. Inclusion ratio: 1 − 1 = 0. Every future distribution to a grandchild is GST-tax-free, no matter how much the trust grows.

Transfer $10 million but allocate only $5 million of exemption. Applicable fraction: 0.50. Inclusion ratio: 0.50. Effective GST rate on future transfers: 40% × 0.50 = 20%. The trust is now a mixed-ratio trust, which every distribution has to reckon with.

Reductions to the Denominator

The denominator is not always gross value. It is reduced by any federal estate or state death tax charged to and actually recovered from the trust, and by any charitable deduction allowed for the transferred property.¹² A lower denominator means less exemption is needed to reach zero.

Structuring the Trust to Keep the Ratio at Zero

Most planners fund the trust only up to the amount their available exemption can cover, keeping the inclusion ratio at zero rather than creating a partially exempt trust. When assets exceed the combined exemption, the standard move is to create separate exempt and non-exempt trusts rather than blend the two in one instrument.

Dynasty Length

The most common GST trust structure is a dynasty trust, designed to last as long as state law allows. Roughly half of U.S. states have either abolished or significantly relaxed the traditional rule against perpetuities, which historically capped trust duration at about 90 years. In those states a trust can run for centuries or indefinitely, compounding tax-free growth across generations.

Powers of Appointment

Beneficiaries should receive only limited powers of appointment, such as the power to direct trust assets among your descendants. If a beneficiary holds a general power of appointment, the IRS treats the trust assets as part of that beneficiary’s taxable estate.¹³ That pulls the assets back into the transfer tax system and defeats the point of the trust. Drafting the right kind of limited power is one of the highest-stakes details in the document.

Crummey Withdrawal Powers

Contributions to a GST trust are gifts of a future interest and do not automatically qualify for the annual gift tax exclusion (currently $19,000 per recipient). To turn them into present-interest gifts, the trust gives each beneficiary a temporary right to withdraw their share of each contribution. These are Crummey powers, named after a 1968 Tax Court case. Every time the trust is funded, the trustee has to send written notice to the beneficiaries describing the withdrawal right and giving them a reasonable window to exercise it. Beneficiaries almost never withdraw. The legal right is what qualifies the gift for the exclusion. Skip the notices or shorten the window unreasonably and the exclusion is lost, which forces you to allocate more exemption to cover the transfer.

Fixing a Mixed-Ratio Trust With Qualified Severance

A trust with an inclusion ratio between zero and one is an administrative headache. Every distribution to a skip person triggers a partial tax, and the trustee has to track fractional exposure indefinitely. Federal law offers a fix called a qualified severance, which splits the trust in two.¹¹ To qualify:

The trust must be divided fractionally, not by fixed dollar amount. Each new trust gets a percentage of every asset.
The resulting trusts, taken together, must provide the same succession of beneficiary interests as the original.
One new trust must receive a fractional share equal to the applicable fraction of the original (the exempt portion) and the other receives the remainder. After the split, one trust has an inclusion ratio of zero and the other has an inclusion ratio of one.

The exempt trust can then distribute to skip persons with no GST tax. The taxable trust can be managed or drawn down differently. A severance can be done at any time, so trustees can clean up mixed-ratio trusts long after they were created.¹¹

Filings and Valuation Risk

GST trust administration runs through several IRS forms, and missing a deadline or picking the wrong form can waste exemption or trigger penalties.

Every lifetime transfer to a GST trust needs a Form 709 for that calendar year, even if no gift tax is due.⁷ The return reports both the gift and the GST exemption allocation. Filing on time locks in the transfer-date value for the inclusion ratio.

At death, the executor allocates any remaining exemption on Form 706. Because there is no portability, filing to preserve unused GST exemption is not optional the way it can be for estate tax portability. If the executor does not allocate, the exemption disappears.

When a trust makes a taxable distribution, the skip person receiving it, not the trust, owes the tax and files Form 706-GS(D).¹⁴ The trustee’s role is to provide the beneficiary the information needed to complete the return, using Form 706-GS(D-1).¹⁵ When a taxable termination happens, the trustee both files and pays the tax on Form 706-GS(T) for the year of the termination.¹⁶

Valuation is where the whole plan can unravel. The inclusion ratio depends entirely on the denominator, so understating the value of transferred property inflates the applicable fraction and makes the trust appear more exempt than it really is. If the IRS finds the property was undervalued, the resulting underpayment can carry an accuracy-related penalty of 20% of the underpayment.¹⁷ For closely held business interests, real estate, and other hard-to-value assets, a qualified appraisal at the time of transfer is the primary defense.

1
Internal Revenue Service. Whats New – Estate and Gift Tax
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Office of the Law Revision Counsel. 26 USC 2613 – Skip Person and Non-Skip Person Defined
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Office of the Law Revision Counsel. 26 US Code 2651 – Generation Assignment
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Office of the Law Revision Counsel. 26 US Code 2611 – Generation-Skipping Transfer Defined
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Office of the Law Revision Counsel. 26 US Code 2641 – Applicable Rate
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Office of the Law Revision Counsel. 26 USC 2631 – GST Exemption
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Internal Revenue Service. About Form 709, United States Gift (and Generation-Skipping Transfer) Tax Return
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eCFR. 26 CFR 26.2632-1 – Allocation of GST Exemption
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eCFR. 26 CFR 26.2642-2 – Valuation
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Office of the Law Revision Counsel. 26 US Code 2010 – Unified Credit Against Estate Tax
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Office of the Law Revision Counsel. 26 USC 2642 – Inclusion Ratio
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eCFR. 26 CFR 26.2642-1 – Inclusion Ratio
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Office of the Law Revision Counsel. 26 USC 2041 – Powers of Appointment
14
Internal Revenue Service. About Form 706-GS(D), Generation-Skipping Transfer Tax Return for Distributions
15
Internal Revenue Service. Instructions for Form 706-GS(D-1) – Notification of Distribution From a Generation-Skipping Trust
16
Internal Revenue Service. About Form 706-GS(T), Generation Skipping Transfer Tax Return for Terminations
17
Office of the Law Revision Counsel. 26 US Code 6662 – Imposition of Accuracy-Related Penalty on Underpayments