Irrevocable Trust: How It Works, Types, and When You Need One

An irrevocable trust permanently transfers assets out of your taxable estate. Once you fund it, you can't change the terms, reclaim the assets, or undo the transfer. That inflexibility is the entire point — it's what gets assets outside your estate for tax purposes, protects them from creditors, and lets them compound for heirs across generations. This guide covers how irrevocable trusts work, the key types, how they're taxed, and how to pick the right structure for your situation.

Irrevocable trust vs. revocable trust

Most estate plans start with a revocable living trust — it avoids probate but does nothing for estate tax because you retain full control and the assets stay in your taxable estate. An irrevocable trust does the opposite: you give up control, and in exchange the assets leave your taxable estate.

How irrevocable trusts work for estate planning

Step 1: You fund the trust — and use exemption

Transferring assets to an irrevocable trust is a completed gift. You'll use your lifetime gift and estate tax exemption (or pay gift tax if you've exhausted it). In 2026, each individual has $15,000,000 of combined lifetime gift and estate tax exemption.¹ A married couple has $30M. Most HNW families fund irrevocable trusts during their lifetime to use exemption now and remove future appreciation from the estate.

The annual gift exclusion — $19,000 per recipient per year (2026)² — can also be used to fund certain trusts without touching the lifetime exemption, but this requires the trust to include Crummey withdrawal rights for beneficiaries.

Step 2: Assets leave your estate — and future appreciation goes with them

Once the trust is funded, the assets and all future appreciation compound outside your taxable estate. If you contribute $2M to an irrevocable trust and it grows to $8M over 20 years, only $2M used exemption. The $6M of appreciation transferred tax-free. At 40% estate tax rates, that's $2.4M in avoided tax that would have been owed if you'd held the asset directly.

Step 3: No step-up in basis at your death

This is the key trade-off. Under IRC §1014, assets included in your taxable estate receive a step-up (or step-down) in basis to fair market value at death — eliminating embedded capital gains. Assets in an irrevocable trust excluded from your estate don't get that step-up. Heirs inherit the trust's original cost basis, paying capital gains tax when they sell.

For high-growth assets (startup equity, real estate with large gains, appreciated stock), the estate tax savings from moving the asset out of the estate typically dwarf the lost step-up. For low-growth or fully depreciated assets near current fair market value, holding until death for the step-up may be better. Your advisor can run the trade-off analysis.

Grantor trust vs. non-grantor trust: the income tax distinction

Most irrevocable trusts are structured as grantor trusts for income tax purposes — meaning the trust's income, dividends, and capital gains are taxed to you personally, not the trust. This sounds bad but is actually a feature:

• Your tax payments on trust income are additional tax-free gifts to the trust (you're paying the trust's tax bill, which reduces your estate at no gift tax cost).
• The trust grows 100% undiluted by income tax while you're alive.
• High-bracket trusts avoid the compressed trust tax brackets described below.

Non-grantor trusts pay their own income tax. The problem: trust income tax brackets are extremely compressed. In 2026, a non-grantor trust hits the top 37% federal income tax rate at approximately $15,200 of taxable income.³ An individual doesn't reach 37% until $609,350. The 3.8% net investment income tax (NIIT) also applies to trust investment income above approximately $15,650.³ For trusts with meaningful investment income, total federal rates can reach 40.8% on ordinary income.

Types of irrevocable trusts

There's no single "irrevocable trust" — it's a family of strategies, each designed for a specific estate planning goal. The right type depends on your assets, family structure, and primary objective.

Estate tax removal with family access

Spousal Lifetime Access Trust (SLAT)

You make a gift to an irrevocable trust for your spouse's benefit. Assets are out of your estate; your spouse can still access income and principal under the trust terms. The big risk: divorce or death of the spouse ends access. Dual-SLAT strategies (each spouse funds a trust for the other) can preserve indirect access for both spouses but must be structured carefully to avoid the IRS reciprocal trust doctrine.

Best for: Married couples who want to remove assets from their estate while preserving indirect access through the spouse. Post-OBBBA, SLATs are still valuable for estates above $15M, state estate tax planning, and asset protection.

Transfer of appreciation

Grantor Retained Annuity Trust (GRAT)

You contribute assets to the trust, then receive a fixed annuity payment back each year for a term. The IRS calculates the "retained interest" using the §7520 rate (5.00% in May 2026). If the assets grow faster than that rate, the excess appreciation passes to heirs at little or no gift tax cost. Zeroed-out GRATs are common — the annuity is set so the remainder has essentially $0 present value, meaning minimal exemption is used even on large asset transfers.

Best for: High-growth assets (pre-IPO stock, real estate about to appreciate, business interests) where you expect returns well above the §7520 hurdle. Works in any rate environment — lower §7520 rates make GRATs more efficient. If you die during the term, all assets return to your estate, so shorter terms are safer.

Intentionally Defective Grantor Trust (IDGT) — Installment Sale

You sell assets to an IDGT in exchange for a promissory note at the applicable federal rate (AFR, 4.08% mid-term May 2026). Because it's a sale to a grantor trust, there's no capital gains recognition under Rev. Rul. 85-13. The trust pays you interest and principal; you move the full value out of your estate immediately. Unlike a GRAT, no mortality risk — if you die before the note is paid, only the note value (not the full trust assets) returns to your estate.

Best for: Large asset transfers of $5M+ where mortality risk of a GRAT is a concern, business interests where installment sale mechanics are practical, or situations where the asset's expected return far exceeds AFR.

Multi-generational planning

Dynasty Trust

An irrevocable trust designed to hold assets for multiple generations — children, grandchildren, and beyond — funded with GST exemption so assets pass through generations without estate or generation-skipping tax. States like South Dakota, Nevada, Delaware, and Wyoming allow perpetual trusts. The math: a $10M dynasty trust growing at 7%/year reaches ~$150M in 40 years, all outside the estate and without GST tax at any generational transfer.

Best for: Families who want to create lasting generational wealth, have GST exemption available, and are willing to subject assets to trust governance in perpetuity. Often structured as a grantor trust initially for the income-tax benefits.

Real estate and personal residence

Qualified Personal Residence Trust (QPRT)

You transfer your home to an irrevocable trust but retain the right to live there for a fixed term (say, 10 years). The gift value at funding is discounted heavily — you're only giving away the remainder interest. At the end of the term, the home passes to children (or other beneficiaries) at the discounted value. If you want to continue living there, you pay fair market rent, which transfers additional wealth at no gift tax cost.

Best for: High-value primary residences or vacation homes where the appreciation is expected to be significant and you're comfortable with the planning horizon.

Insurance and liquidity

Irrevocable Life Insurance Trust (ILIT)

The trust owns a life insurance policy on your life. Because you don't own the policy (the trust does), the death benefit is excluded from your taxable estate under IRC §2042. The policy proceeds can be used to pay estate taxes on illiquid assets, equalize inheritances, or provide liquidity for heirs. Crummey notices allow annual gift exclusion contributions to fund premiums without using lifetime exemption.

Best for: Families with illiquid taxable estates (business, real estate) who need cash to pay estate taxes at death without forcing heirs to sell assets.

Charitable strategies

Charitable Remainder Trust (CRT)

You contribute appreciated assets and receive an income stream (fixed annuity or variable unitrust) for your lifetime. The charity receives the remainder. You get an immediate charitable deduction for the present value of the remainder, and the trust sells the asset without recognizing capital gains. A powerful strategy for large, appreciated, low-basis positions you want to monetize.

Best for: Donors with large appreciated assets who want income, a charitable deduction, and to avoid the capital gains hit on a sale. Requires genuine charitable intent — the charity must receive a meaningful remainder (the IRS 10% test).

Charitable Lead Annuity Trust (CLAT)

The charity gets an income stream first; the remainder passes to heirs. The remainder value — what transfers to heirs — is calculated at the §7520 rate. If trust assets outperform that rate, the excess passes to heirs gift-tax free (similar mechanic to a zeroed-out GRAT, but with a charitable income stream rather than an annuity back to you).

Best for: Families who want to transfer wealth to heirs while making a meaningful charitable gift during the trust term. Works best when the §7520 rate is low relative to expected trust returns.

Special situations

Special Needs Trust (SNT)

An irrevocable trust designed to benefit a disabled beneficiary without disqualifying them from Medicaid or SSI. Third-party SNTs (funded by parents/grandparents) allow assets to supplement government benefits, covering quality-of-life expenses that benefits don't pay — travel, equipment, recreation, education. GST exemption can be allocated to SNTs for multi-generational benefit.

Best for: Families with a disabled child, grandchild, or other beneficiary who relies on or may rely on means-tested government benefits.

Irrevocable trust pros and cons

The step-up basis trade-off in detail

The single biggest planning question around irrevocable trusts: is the estate tax savings worth losing the step-up in basis?

The math usually favors the trust for high-growth assets. Here's a simplified example:

Assumes estate above exemption threshold. The higher the estate and the more the asset appreciates, the more decisive the trust wins.

The calculus reverses for assets that won't appreciate much, assets with a basis near fair market value, or when the estate is unlikely to be taxable (under the $15M exemption). In those cases, holding until death and capturing the step-up can be the better move. See the step-up basis calculator to model your specific situation.

Common mistakes

1. Retaining too much control. If you retain certain powers over an irrevocable trust — the power to revoke, control beneficial enjoyment, or change beneficiaries — the IRS will pull assets back into your estate under IRC §§2036–2038. The trust must be genuinely irrevocable and controlled by an independent trustee or limited by carefully drafted ascertainable standards.
2. The reciprocal trust doctrine. Spouses who each fund SLATs for the other on substantially identical terms risk the IRS "uncrossing" the trusts under United States v. Grace, treating the assets as included in each spouse's estate. Differentiate the terms, assets, trustees, and timing.
3. Unfunded trusts. An irrevocable trust with no assets is a legal document, not an estate plan. The trust doesn't do anything until assets are actually transferred into it — with proper deeds, account re-registration, and assignment agreements.
4. Wrong assets in the trust. Putting IRA or 401(k) funds directly into an irrevocable trust creates an immediate taxable distribution. Retirement accounts with large embedded IRD should generally stay outside irrevocable trusts, distributed to beneficiaries who then make contributions, or handled through IRA/Roth conversion strategies. See the IRA estate planning guide.
5. Not allocating GST exemption. Funding a dynasty trust without properly allocating GST exemption at funding is an irreversible mistake. The trust will have a non-zero inclusion ratio, meaning future distributions to grandchildren or great-grandchildren will trigger GST tax. Work with counsel to make the election on Form 709 in the year of funding.
6. Choosing the wrong trust for the goal. A GRAT makes sense for a pre-IPO stock position. An ILIT makes sense for funding estate tax liquidity. A SLAT makes sense for married couples who want indirect access. Using the wrong structure for your specific goal wastes exemption, creates unnecessary complexity, and may not achieve the intended result.

Choosing the right irrevocable trust