Estate Tax Portability Election Calculator 2026 β DSUE & Form 706 Analysis
Calculate the deceased spouse's unused exemption (DSUE), combined estate protection, and Form 706 cost-benefit analysis using the 2026 $15,000,000 federal estate tax exemption.
Portability Election Analysis
Form 706 Cost vs. Benefit
How the Portability Election Works
When a spouse dies, any portion of their $15,000,000 federal estate tax exemption that was not used can be "ported" to the surviving spouse. The executor must make this election by filing Form 706, even if no estate tax is owed.
DSUE Calculation Formula
DSUE = $15,000,000 − Deceased's Used Exemption
Surviving Spouse's Total Exemption = $15,000,000 + DSUE
Combined Protection = Up to $30,000,000
Example: $8M Estate, $12M Surviving Spouse
Used exemption: $8,000,000
DSUE: $15,000,000 − $8,000,000 = $7,000,000
Surviving spouse: $12M estate + $7M DSUE
Total exemption: $15M + $7M = $22,000,000
Taxable estate: $12M − $22M = $0 (fully protected)
Without portability: $12M − $15M = $0 (also protected here, but grows over time)
When Portability Really Matters
Portability becomes critical when the surviving spouse's estate is expected to grow above $15,000,000, or when assets are concentrated and couldn't easily be split between spouses during life. It is also the primary strategy for couples who did not establish a credit shelter (bypass) trust.
Estate Size Scenario Analysis
See tax savings from portability across different estate sizes from $5M to $50M
Estate Size Scenario Analysis
Portability benefit at different combined estate sizes. Assumes first spouse dies with half the estate, no lifetime gifts made, surviving spouse inherits everything.
| Deceased Estate | Survivor Estate | DSUE | Tax Without Portability | Tax With Portability | Tax Saved | Form 706 Worth It? |
|---|
Portability vs. Credit Shelter Trust
Portability is simpler but has limitations. A credit shelter (bypass) trust locks in the exemption at death and allows the trust assets to grow outside the estate. This is superior when you expect significant future appreciation. However, portability works well for smaller estates or those who did not establish a trust before the first death.
| Factor | Portability | Credit Shelter Trust |
|---|---|---|
| Simplicity | Simpler β just file Form 706 | Requires trust setup before death |
| Growth on exemption | DSUE is fixed β no growth | Trust assets grow outside estate |
| State estate tax | No state portability in most states | Protects state exemption too |
| Remarriage risk | DSUE lost if new spouse predeceases | Trust unaffected by remarriage |
| Cost | $5Kβ$15K Form 706 | $3Kβ$10K trust + Form 706 |