Deceased Spouse Unused Exclusion (DSUE): How Portability Protects Surviving Spouses

When your spouse dies and their estate doesn't use the full federal estate tax exemption, the leftover amount doesn't vanish. It can transfer to you. The IRS calls this the Deceased Spouse's Unused Exclusion amount, or DSUE, and it's the mechanism behind what estate planners refer to as "portability."

The catch: it doesn't transfer automatically. You have to file a specific tax return to claim it, even when no estate tax is owed. Skip that filing and the unused exemption disappears permanently.

What the DSUE Actually Is

Every individual gets a federal estate tax exemption — the amount they can pass to heirs without triggering the 40% federal estate tax. For 2026, that exemption is $15,000,000 per person.

If someone dies with a $3 million estate, they've used $3 million of their $15 million exemption. The remaining $12 million is the DSUE — the deceased spouse's unused exclusion. Portability allows the surviving spouse to add that $12 million to their own $15 million exemption, creating a combined shield of $27 million.

Without portability, each spouse's exemption is independent. The first spouse's unused portion simply evaporates at death unless it was sheltered in a bypass trust or other planning structure created before death.

How to Claim the DSUE

The executor of the deceased spouse's estate must file IRS Form 706 (United States Estate and Gift Tax Return) and explicitly elect portability. This filing is required even when the estate is well below the $15 million threshold and owes zero estate tax.

Key requirements:

• Form 706 must be filed. There is no simplified form, no checkbox on Form 1040, and no alternative method. The full estate tax return is the only vehicle for the portability election.
• The filing deadline is 9 months after the date of death. An automatic 6-month extension is available by filing Form 4768 before the deadline, pushing the outer limit to 15 months after death.
• Late filing is possible under Rev. Proc. 2022-32. If the executor missed the original deadline, the IRS allows a simplified late portability election for estates that fall below the filing threshold. The return must be filed within 5 years of the date of death and must include the statement "FILED PURSUANT TO REV. PROC. 2022-32" at the top.

The surviving spouse doesn't file anything — the election is made entirely on the deceased spouse's estate return.

When the DSUE Matters Most

For married couples with combined assets well under $30 million, portability might seem irrelevant today. But exemption amounts change with legislation. The current $15 million exemption was increased under the One Big Beautiful Bill Act. If Congress lowers the exemption in the future, a surviving spouse who locked in the DSUE from years earlier would retain that higher amount.

Portability matters immediately when:

• The surviving spouse has their own substantial assets. A surviving spouse worth $10 million who inherits a $12 million DSUE now has $27 million in combined exemption instead of $15 million.
• The deceased spouse made large lifetime gifts. Taxable gifts during life reduce the available exemption at death. If someone gave away $5 million above the annual exclusion during their lifetime, their remaining exemption at death is $10 million — which becomes the DSUE amount.
• The couple didn't use a bypass trust. Bypass (credit shelter) trusts were the standard estate planning tool before portability existed. Couples without trusts now rely entirely on portability to preserve both exemptions.

What the DSUE Doesn't Cover

Portability applies only to the federal estate and gift tax exemption. It does not transfer:

• Generation-skipping transfer (GST) tax exemption. The $15 million GST exemption is not portable. If the first spouse didn't allocate their GST exemption to trusts for grandchildren, that amount is lost.
• State estate tax exemptions. States that impose their own estate taxes (like Massachusetts, Oregon, and Connecticut) do not recognize federal portability. Even if the DSUE is fully claimed at the federal level, state taxes apply independently based on each state's own threshold.

The Remarriage Complication

The DSUE is only preserved from the last deceased spouse. If a surviving spouse remarries and the second spouse also dies, the DSUE from the first spouse is replaced by whatever DSUE the second spouse leaves behind — even if it's smaller.

Estate planners often recommend that surviving spouses who remarry and have significant DSUE amounts use their first spouse's DSUE by making taxable gifts before the second spouse's death. Otherwise, the larger exemption could be permanently lost.

State-Specific Considerations

In states like Wyoming that impose no state estate tax, inheritance tax, or income tax, the DSUE election is purely a federal matter. There are no state forms to file and no state-level equivalent to manage. The executor files Form 706 with the IRS, and the surviving spouse's future federal exemption is adjusted accordingly.

For executors navigating Wyoming estate administration alongside the portability election, the Wyoming Final Tax & Estate Tax Guide walks through the complete Form 706 filing process, the DSUE calculation, and how it fits into the broader estate settlement timeline.

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