Understanding Portability of the Estate Tax Exemption

Estate planning can involve several federal tax rules, including the portability of the estate tax exemption. Portability allows a surviving spouse to use the deceased spouse’s unused federal estate and gift tax exclusion, known as the deceased spousal unused exclusion (DSUE) amount. The provision can increase the amount the surviving spouse can transfer without federal estate or gift tax.

If you’re preparing an estate plan, a financial advisor can help you understand key concepts to protect your assets.

How Portability in Estate Planning Works

Portability allows a surviving spouse to add a deceased spouse’s unused federal estate and gift tax exclusion to the surviving spouse’s own available exclusion. The provision was introduced in 2010 and later made permanent.

For 2026, the federal basic exclusion amount is $15 million per individual. This means a married couple could potentially shelter as much as $30 million from federal estate and gift taxes when they properly elect portability and neither spouse has previously used part of the exclusion for taxable transfers.

For example, assume a spouse dies in 2026 without having used any of the $15 million exclusion. If the estate properly elects portability, the surviving spouse could receive a DSUE amount of up to $15 million. That amount would generally be available in addition to the surviving spouse’s own basic exclusion.

The actual DSUE amount depends on how much of the deceased spouse’s exclusion remains unused. Lifetime taxable gifts and taxable transfers at death can reduce the amount available for portability.

Benefits and Limitations of Portability for Spouses in Estate Planning

Portability can make estate planning more flexible. It makes it so a couple does not necessarily need to divide assets between spouses solely to preserve both federal exclusions. A surviving spouse who receives a DSUE amount can potentially use it for taxable gifts during life or transfers at death.

However, portability applies to the federal estate and gift tax exclusion. State estate tax systems have their own rules, and portability at the federal level does not automatically provide the same treatment for state estate taxes.

Portability also does not transfer the deceased spouse’s generation-skipping transfer tax exemption. Couples planning transfers to grandchildren or later generations may therefore need strategies beyond portability.

Most importantly, portability is not automatic. The deceased spouse’s estate generally must file Form 706 to elect it. Filing is necessary even when the estate otherwise would not need to file an estate tax return.

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Key Points to Know About Portability

A senior couple discussing the benefits of portability to get estate tax exemptions.

Several rules affect married couples can use portability:

The federal basic exclusion amount can change. For 2026, the exclusion is $15 million per individual, up from $13.99 million in 2025.
Portability is available to a surviving spouse. The amount transferred is the deceased spouse’s unused exclusion, rather than automatically being the full exclusion that was in effect when that spouse died.
The DSUE amount can be used for lifetime taxable gifts. The surviving spouse can apply an available DSUE amount to taxable transfers made after the deceased spouse’s death.
Filing Form 706 is necessary to elect portability. The normal deadline is nine months after death. In some cases, an automatic six-month filing extension may be available.
Certain estates have additional time to make a late election. Under IRS Revenue Procedure 2022-32, an estate that was not otherwise required to file Form 706 may qualify for simplified relief by filing a complete return on or before the fifth anniversary of the spouse’s death. The five-year period is therefore not the standard filing deadline for every portability election.

The executor may want to discuss the election with an estate planning attorney or tax professional even when the estate is well below the federal filing threshold. Once the opportunity to elect portability has passed, the surviving spouse could lose access to the deceased spouse’s unused exclusion.

How Remarriage Can Affect Portability

Portability has an additional rule that can become important when a surviving spouse remarries. The DSUE available for future transfers generally comes from the surviving spouse’s last deceased spouse. Remarriage itself does not eliminate an existing DSUE amount. However, the death of a subsequent spouse can change which deceased spouse is considered the last deceased spouse.

For example, assume a widow receives a $10 million DSUE amount from her first husband and later remarries. The remarriage alone does not prevent her from using that $10 million for taxable gifts. If her second husband subsequently dies, however, the last-deceased-spouse rule can affect the DSUE available for later transfers.

There is an important planning distinction for gifts already made. IRS rules generally apply the DSUE amount before the surviving spouse’s own basic exclusion when the spouse makes a taxable gift. A surviving spouse who expects to remarry may therefore consider whether using some of an existing DSUE amount during life fits into their broader estate plan.

Using Portability for Strategic Gifting

Portability can also affect lifetime gift tax planning. A surviving spouse can use an available DSUE amount to cover taxable gifts made after the deceased spouse’s death rather than reserving the entire amount for the surviving spouse’s estate.

For example, assume a surviving spouse has a $5 million DSUE amount available. The spouse makes a $2 million taxable gift that deductions or exclusions don’t otherwise cover. In that case, the DSUE amount would generally be applied before the surviving spouse’s own basic exclusion.

This is separate from the annual gift tax exclusion. In 2026, an individual can generally give up to $19,000 per recipient under the annual exclusion without using the individual’s lifetime basic exclusion or available DSUE amount.

Large lifetime gifts can have other estate, income and capital gains tax consequences. Because of this, the tax effect depends on more than just the amount of DSUE available.

Bottom Line

A financial advisor goes over the tax rules for using portability in a senior couple's estate plan.

Understanding portability, its benefits and its limitations is an essential component of effective estate planning. Portability is a powerful tool that can maximize estate tax exemption benefits, minimize potential estate taxes and enable strategic gifting. It’s also a dynamic process that requires timely action. Taking advantage of it requires being proactive in understanding your estate’s value, making decisions about portability early on and tracking inflation-adjusted exemption increases yearly.

Tips for Estate Planning

Working with a financial advisor can simplify your estate planning process and help you make sure you’re setting up your estate correctly. Finding a financial advisor doesn’t have to be hard. SmartAsset’s free tool matches you with vetted financial advisors who serve your area, and you can have a free introductory call with your advisor matches to decide which one you feel is right for you. If you’re ready to find an advisor who can help you achieve your financial goals, get started now.
If you’re just starting to get things in order for your estate, consider using an estate planning checklist. This can help you to make sure you’re thinking about the right things.