Estate Tax Portability Calculator
Federal estate tax portability lets a surviving spouse add the deceased spouse's unused exclusion, the DSUE amount, to their own exclusion. The DSUE is the deceased spouse's basic exclusion amount minus what that spouse's estate and lifetime taxable gifts already used. This calculator takes the basic exclusion amount, the exclusion the deceased spouse used, and the surviving spouse's own exclusion, then computes the DSUE and the surviving spouse's combined available exclusion. It also compares the combined exclusion to the surviving spouse's estate to estimate any taxable excess. Confirm the current exclusion with the IRS.
Portability formula
DSUE = max(0, deceased exclusion - exclusion used)
Combined exclusion = surviving spouse exclusion + DSUE
Estate above exclusion = max(0, taxable estate - combined exclusion)
Shielded if taxable estate <= combined exclusion
The estate above the combined exclusion is the amount potentially exposed to federal estate tax before credits and deductions. Actual tax depends on the applicable rate schedule and other factors.
US estate portability context
- Portability must be elected on a timely filed estate tax return (Form 706) for the first spouse to die.
- The DSUE amount is the unused portion of the first spouse's basic exclusion.
- The basic exclusion amount is set by law and indexed for inflation each year.
- The generation-skipping transfer tax exemption is not portable between spouses.
- A surviving spouse can use DSUE from the most recent deceased spouse, subject to ordering rules.
Estate portability: frequently asked questions
What is estate tax portability?
Portability lets a surviving spouse use the deceased spouse's unused estate and gift tax exclusion, called the DSUE amount. The surviving spouse's available exclusion is their own basic exclusion plus the DSUE amount, which can shelter more of the combined estate from federal estate tax.
How is the DSUE amount calculated?
The DSUE amount is generally the deceased spouse's basic exclusion amount minus the exclusion used by that spouse's taxable estate and lifetime taxable gifts. This calculator subtracts the used amount from the deceased spouse's exclusion to find the DSUE.
How do I elect portability?
Portability is not automatic. The executor of the deceased spouse's estate must elect it by filing a timely federal estate tax return (Form 706), even if no tax is otherwise due. Without that election, the DSUE amount is lost.
What exclusion amount should I enter?
Enter the basic exclusion amount in effect for the relevant year as a user-editable input. The exclusion is set by law and indexed for inflation, so confirm the current figure with the IRS before relying on the result.
Does portability apply to the generation-skipping tax?
No. The generation-skipping transfer (GST) tax exemption is not portable between spouses. Portability applies only to the estate and gift tax basic exclusion amount, not the GST exemption.
Official sources
- Internal Revenue Service: Estate Tax.
- Internal Revenue Service: What's New: Estate and Gift Tax.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.