A grantor trust is a trust whose income is taxable to the grantor - not to the trust itself - because the grantor has retained certain powers or interests over the trust. Grantor trust status can be inadvertent (the trust was supposed to be a separate taxpayer) or intentional (the grantor deliberately structures the trust to be a grantor trust for estate planning purposes). Intentionally defective grantor trusts - IDGTs - are one of the most powerful estate planning tools available, allowing asset transfers that are complete for estate tax purposes but invisible for income tax purposes. Mastering the grantor trust rules means understanding both how to trigger grantor trust status and how to turn it off.
For estate tax: A completed gift to an irrevocable trust removes assets from the grantor's estate permanently. Future appreciation accrues to the trust beneficiaries, not the grantor's estate.
For income tax (grantor trust): The trust is ignored entirely. The grantor pays income tax on all trust income as if the assets had never left. This is not a disadvantage - it is the feature. The grantor's payment of trust income taxes is an additional tax-free gift to the trust beneficiaries, further reducing the taxable estate.
The "defect": The trust is "defective" for income tax purposes only - meaning it does not achieve its purpose of being a separate income tax entity. But that defect is intentional and creates the planning opportunity.
Sections 671 through 679 establish when a trust's income, deductions, and credits are taxed to the grantor rather than the trust. The key provisions:
§673: Reversionary interests - if the grantor retains a reversionary interest with a present value exceeding 5% of the trust principal, grantor trust status applies.
§674: Power to control beneficial enjoyment - if the grantor (or a nonadverse party) retains a power to control who receives income or principal, grantor trust status applies. Exceptions exist for independent trustee powers and certain administrative powers.
§675: Administrative powers - retained administrative powers inconsistent with arm's length dealing (power to borrow without adequate interest or security; power to vote or control stock above 20%; power of substitution without fiduciary constraint) trigger grantor trust status.
§676: Power to revoke - if the grantor retains the power to revoke the trust and revest assets in the grantor, it is a grantor trust. This is the classic revocable living trust - entirely a grantor trust.
§677: Income for benefit of grantor - if trust income may be distributed to the grantor or the grantor's spouse, or used to pay premiums on policies insuring the grantor's life, grantor trust status applies.
§678: Person other than grantor treated as owner - if a non-grantor person holds a power to vest trust corpus or income in themselves, that person (not the grantor) is taxed on the trust income. This is the basis for certain beneficiary-controlled trust structures.
The most powerful IDGT application is the installment sale of appreciated assets to a grantor trust in exchange for a promissory note. Because the grantor trust is ignored for income tax purposes, a sale between the grantor and the grantor trust is invisible to the income tax system - no gain is recognized on the sale, no interest income is recognized on the note payments. The economics: the grantor transfers appreciating assets out of the estate at today's value; the trust pays with a note at the applicable federal rate (AFR); future appreciation above the AFR accrues to the trust beneficiaries income and estate-tax free. This is more efficient than a GRAT for assets expected to appreciate significantly above the AFR.
Practitioners typically use one of three mechanisms to create intentional grantor trust status in an IDGT: (1) the substitution power under §675(4) - the grantor retains the power to reacquire trust assets by substituting assets of equivalent value; (2) a non-adverse party holds the power to add beneficiaries under §674; or (3) the trust can loan funds to the grantor without adequate security under §675(2). The substitution power is the most commonly used because it does not affect the trustee's independent management authority and is least likely to cause inclusion in the grantor's estate.
If the grantor's income tax burden from trust income becomes prohibitive, grantor trust status can be terminated by releasing the triggering power. Once terminated, the trust becomes a non-grantor trust and files its own Form 1041, paying tax at compressed trust tax rates (the 37% rate applies above $15,650 of trust taxable income for 2026). The termination is a taxable event only if the release constitutes a deemed distribution - which it generally does not under a substitution power release.