Surviving Spouse Estate Tax in New York: Marital Deduction, Portability, and the Step-Up Trap

The death of a spouse in New York triggers a set of tax consequences that most surviving spouses discover too late. The immediate transfer may be tax-free. But the structural problem — the permanent loss of the deceased spouse's New York estate tax exemption — is invisible at first and often very expensive later.

The Unlimited Marital Deduction

Both federal and New York estate tax law provide an unlimited marital deduction: assets passing from one spouse to a surviving spouse are completely exempt from estate tax at the time of the first death, regardless of amount.

If your spouse dies with a $10,000,000 estate and leaves everything to you, no New York or federal estate tax is due at that point. The marital deduction absorbs the entire transfer.

This feels like a clean solution. It's not. The problem emerges when the surviving spouse later dies.

New York Has No Portability

The federal estate tax system includes portability: if a spouse dies without using their full exclusion amount, the surviving spouse can "inherit" the unused portion. For 2026, the federal exclusion is $15,000,000 per person. If Spouse A dies and leaves everything to Spouse B without using their exclusion, Spouse B can elect to carry forward Spouse A's unused exclusion — meaning Spouse B potentially has a combined exclusion of $30,000,000. Portability is elected by filing a timely federal Form 706 after the first death, even if no federal tax is owed.

New York does not have portability. There is no mechanism in New York law to transfer the deceased spouse's unused New York exclusion to the survivor.

This creates a silent but devastating problem: if Spouse A dies and leaves everything outright to Spouse B, Spouse A's $7,350,000 New York exclusion is permanently gone. When Spouse B later dies with the combined assets, only Spouse B's $7,350,000 exclusion is available to shield the estate. Everything above $7,350,000 is potentially taxable at rates up to 16%.

For a couple with a combined estate of $14,000,000 where everything passed to the survivor at the first death, the surviving spouse's estate faces potential New York estate tax on roughly $6,650,000 — a tax bill that could easily exceed $1,000,000 and that could have been entirely avoided with proper planning.

The Solution: Credit Shelter Trust

Estate attorneys solve the New York portability gap with a credit shelter trust (also called a bypass trust or B trust). The structure is straightforward: when the first spouse dies, their will directs an amount equal to the New York exclusion amount ($7,350,000 in 2026) into a trust rather than outright to the surviving spouse.

The trust must benefit the surviving spouse — typically providing income, and often principal access under certain conditions — but the trust assets are not included in the surviving spouse's gross estate at their later death.

At the second death, the surviving spouse's own exclusion shields their estate. The credit shelter trust funds are distributed separately, having already been sheltered by the first spouse's exclusion at the first death.

Result: the family has used both spouses' $7,350,000 exclusions, shielding up to $14,700,000 from New York estate tax. Without the trust, only one exclusion is available.

The trust must be funded correctly at death, which requires up-to-date estate planning documents. A will that directs "everything to my spouse" does not create a credit shelter trust. This type of provision must be explicitly drafted by an attorney while the first spouse is alive.

Filing Federal Form 706 for Portability — Even Without NY Benefit

Even though New York doesn't recognize portability, there may still be a reason to file federal Form 706 after the first spouse's death: to preserve the federal portability election for the survivor's future federal estate tax exposure.

For a couple with a combined estate well below the $15,000,000 federal threshold, the federal portability election may not matter today. But federal exclusion amounts can and do change with legislation, and locking in the deceased spouse's unused federal exclusion costs only the time and expense of filing Form 706.

The federal Form 706 must be filed within nine months of death (or within the extension period under Form 4768) to preserve the portability election. Waiting until the surviving spouse is near death and concerned about federal exposure is too late.

The Step-Up in Basis for Jointly Owned Property

On the capital gains side, New York's status as a common law state (as opposed to a community property state) creates a meaningful disadvantage for surviving spouses inheriting jointly owned property.

In community property states (California, Texas, Arizona, etc.), both halves of jointly held marital property receive a step-up in basis at the first spouse's death. In common law states like New York, only the deceased spouse's half gets the step-up.

Example: A married couple in Westchester purchased their home together in 2000 for $600,000, each contributing to the $300,000 basis for their respective half. The home is worth $1,800,000 when the first spouse dies in 2026.

The deceased spouse's 50% interest ($900,000 FMV) is stepped up to $900,000. The surviving spouse's 50% remains at the original $300,000 basis.

If the surviving spouse sells the home for $1,800,000 a few years later:

• Surviving spouse's half: $900,000 sale price minus $300,000 basis = $600,000 taxable gain
• Deceased spouse's stepped-up half: $900,000 sale price minus $900,000 basis = $0 gain
• Total capital gain: $600,000

After the $250,000 primary residence exclusion (single filer after first spouse's death), the surviving spouse owes capital gains tax on $350,000.

Had the property been in a community property state, both halves would have been stepped up to $1,800,000 total, resulting in zero capital gain.

This is not something you can fix after the first death. It's a structural feature of New York property law. Couples with significant real estate appreciation should understand this dynamic when considering the timing of any sale.

What Surviving Spouses Should Do in the First Nine Months

After a spouse's death in New York, the surviving spouse or their attorney should:

1. Evaluate whether federal Form 706 should be filed for portability purposes, even with no federal tax owed (due by nine months from date of death, with extension available via Form 4768)
2. Assess the New York estate tax exposure using the actual date-of-death values — not estimates — to determine whether the ET-706 is required
3. Get a date-of-death appraisal for all real estate and closely held business interests to document the step-up in basis
4. Review whether credit shelter trust provisions in the existing estate plan were properly structured and will use the deceased spouse's exclusion

The New York Final Tax & Estate Tax Guide covers the estate tax filing obligations after a spouse's death in New York, including the ET-706 process, the federal Form 706 portability election, and the interaction with New York's credit shelter trust requirements.

For a surviving spouse with a combined estate that may approach $7,350,000 eventually — after including all assets, retirement accounts, life insurance proceeds, and any three-year gift addbacks — the planning steps taken in the first nine months after the first spouse's death can save the family a substantial amount at the second death.

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