Grantor Trust Income Tax 2026 Calculator
Under IRC §671-679 deemed owner rules, the grantor of an intentionally defective grantor trust (IDGT) is taxed on all trust income. This calculator compares the tax bill paid by the grantor versus the same income taxed inside a non-grantor trust at the compressed 37% bracket (which hits at just $15,200 of trust income in 2026).
| Grantor Trust (IRC §671-679 — Grantor Taxed) | |
| Trust income taxed to grantor | — |
| Applicable federal rate | — |
| State rate | — |
| NIIT (if applicable) | — |
| Total tax paid by grantor | — |
| Non-Grantor Trust (Compressed Brackets) | |
| Trust income (taxed at trust level) | — |
| Federal tax at compressed brackets | — |
| Hits 37% bracket at | $15,200 (2026) |
| Total tax paid by trust | — |
| Tax "Burn" — Estate Reduction Effect | |
| Grantor pays tax with personal funds | — |
| Estate reduced annually (40% est. tax saved) | — |
| Trust assets compound tax-free | Yes |
A grantor trust under IRC §671-679 is one where the grantor retains certain powers (or the trust contains certain provisions) that cause the IRS to treat the grantor as the deemed owner for income tax purposes. An "intentionally defective" grantor trust (IDGT) is built so that the trust is excluded from the grantor's estate for transfer tax purposes but the grantor still pays income tax on trust earnings — a powerful combination for high-net-worth estate planning in 2026.
How IRC §671-679 Trigger Grantor Status
The Code contains a list of "defects" that make a trust a grantor trust: §673 reversionary interest worth more than 5%, §674 power to control beneficial enjoyment, §675 administrative powers (the most common — power to substitute assets of equivalent value), §676 power to revoke, §677 income for the grantor's benefit, §678 power held by a non-adverse party, §679 foreign trust with US beneficiary. Most IDGTs use §675(4) — the swap power — because it triggers grantor status without estate inclusion.
Why the 2026 Compressed Trust Brackets Hurt Non-Grantor Trusts
Non-grantor trusts reach the top 37% federal bracket at just $15,200 of taxable income in 2026 — versus $626,350 for a single individual. Long-term capital gains hit the 20% rate at $15,200 too. Add the 3.8% net investment income tax and trusts pay a 40.8% effective federal rate on dollar one above the threshold. This is why letting income accumulate inside a non-grantor trust is rarely tax-efficient unless the trust distributes the income via the DNI rules.
The Tax "Burn" — How IDGTs Shrink the Estate
Because the grantor pays trust income tax from personal funds, every dollar of tax paid is a dollar removed from the grantor's taxable estate without using any gift tax exemption. Rev Rul 2004-64 confirmed that the grantor's payment of trust tax is not a gift to the trust. Over 20 years, this "burn" can shift millions of estate-taxable assets to beneficiaries at a 40% estate-tax savings — while the trust's assets compound tax-free at the trust level.
Strategic Use of Grantor Trusts in 2026
The 2026 unified exemption is $13.99M (permanent under OBBB 2025), but the 40% estate tax above that threshold makes "burn" valuable for estates over $20-30M. Common patterns: (1) Spousal Lifetime Access Trust (SLAT) — IDGT with spouse as beneficiary; (2) IDGT with installment sale of appreciating asset (no gain recognized because grantor is deemed owner, per Rev Rul 85-13); (3) Toggle off grantor status (release swap power) in low-burn years to stop the income tax bleed when no longer needed.
Last updated May 2026. Sources: IRC §671-679, Rev Rul 85-13 (sales to grantor trusts not recognized), Rev Rul 2004-64 (grantor's tax payment not a gift), IRS Rev Proc 2024-40 (2026 trust bracket amounts).