Estate tax portability is the rule that lets a surviving spouse add whatever part of the federal estate tax exclusion their late spouse did not use to their own exclusion — but only if the executor of the first spouse’s estate files a federal estate tax return and formally elects it. The transferred amount has a name in the statute and on the form: the deceased spousal unused exclusion amount, abbreviated DSUE. Portability is not automatic, it is not retroactive by default, and it is lost permanently if nobody files.
The rule was made permanent by the American Taxpayer Relief Act of 2012 and lives in Internal Revenue Code section 2010(c). Before it existed, a couple who left everything outright to each other frequently wasted the first spouse’s exclusion entirely, which is why credit shelter trusts were standard drafting for decades. Portability changed the default, and that is exactly why it is so often confused with the trust technique it partly replaced.
This page defines portability by contrast — against the bypass trust, against stepped-up basis, and against the generation-skipping transfer tax exemption — because those three are where families and even some advisors blur the lines. Confirm every figure below with the IRS or your own CPA before acting; these amounts change by statute and by annual inflation adjustment.
In This Article
The Numbers, and Why They Are Moving
The federal estate tax applies only above the basic exclusion amount. For decedents dying in 2026, the One Big Beautiful Bill Act, signed in July 2025, set that basic exclusion amount at $15 million per person, indexed for inflation in later years. It replaced the scheduled sunset of the 2017 Tax Cuts and Jobs Act amounts that had been expected to cut the exclusion roughly in half at the end of 2025. Confirm the current-year figure with the IRS or your CPA before you plan around it — this number has changed by act of Congress three times since 2010.
Two consequences follow. First, with portability a married couple can in principle shelter double the individual amount, subject to the election being made. Second, at that level of exclusion, the overwhelming majority of American households will never owe federal estate tax at all. As a matter of scale, IRS Statistics of Income data have shown federal estate tax returns reporting a taxable estate numbering in the low thousands per year nationally — a tiny fraction of annual deaths.
That does not make portability irrelevant to ordinary families, for one reason: you cannot know today what the exclusion will be in the year the surviving spouse dies. The exclusion has been $675,000 within recent memory, $5 million, and $15 million. Electing portability preserves an option at a modest filing cost. Failing to elect it forecloses that option forever. That asymmetry is the entire practical argument.
Separately, do not confuse the estate exclusion with the annual gift tax exclusion, which is a per-recipient, per-year amount — $18,000 in 2024 and $19,000 in 2025, adjusted annually. The two interact but they are not the same number, and the annual gift tax exclusion has its own rules.
Portability Versus the Bypass Trust
This is the comparison that matters most, because the two solve the same problem in opposite ways.
A credit shelter trust — also called a bypass trust, a family trust, or a B trust — funds a trust at the first death with an amount equal to the unused exclusion. The surviving spouse can typically receive income and, under standards written into the document, principal. The assets are excluded from the survivor’s taxable estate when they die, and all appreciation between the two deaths escapes estate tax as well.
Portability does nothing at the first death. The assets pass outright to the survivor, the DSUE amount is recorded, and the survivor simply has a larger exclusion later.
Four real differences drive the choice, and none of them is about tax rate.
- Appreciation. The trust shelters growth. The DSUE amount is frozen at the dollar figure computed at the first death and is not indexed for inflation afterward. In a long widowhood with strong asset growth, the trust wins on this factor alone.
- Basis. Trust assets do not get a second step-up in basis at the survivor’s death. Assets held outright do. For a family with highly appreciated stock or real estate and no estate tax exposure, that reverses the answer.
- Creditor and remarriage protection. A trust controls where the money goes after the survivor dies. Portability does not. In blended families this is usually the deciding factor and it has nothing to do with taxes.
- The last deceased spouse rule. A surviving spouse may use the DSUE only of their most recent deceased spouse. Remarry, and a later spouse’s death replaces the earlier DSUE. A trust is not exposed to that risk.
Neither approach is universally better. The point is that the choice is made in the nine months after a death, and defaulting into portability by accident is not the same as choosing it. If a plan was drafted when the exclusion was far smaller, it may now do the wrong thing — a common and fixable problem covered at what to do when the estate plan changed.
Portability Versus Stepped-Up Basis
These get conflated constantly, and they are not the same tax.
Portability is about the estate tax: a transfer tax on the value of what a person owned at death. Stepped-up basis is about income tax: under Internal Revenue Code section 1014, most property included in a decedent’s gross estate takes a new income tax basis equal to its fair market value at the date of death, wiping out the unrealized capital gain for the heirs.
You can have one without the other. An estate below the exclusion pays no estate tax and still gets the basis step-up. A bypass trust preserves exclusion but gives up the second step-up on trust assets. In community property states, the entire community property interest can receive a step-up at the first spouse’s death, which changes the analysis again.
Two things do not get a step-up. Retirement accounts and other items classified as income in respect of a decedent are expressly excluded from section 1014 treatment. And life insurance death benefits do not need one, because they are generally excluded from the recipient’s gross income under section 101(a) in the first place. The persistent myths in this area are collected at the stepped-up basis misconception.
| Feature | Portability (DSUE) | Credit Shelter / Bypass Trust |
|---|---|---|
| Action required at first death | File Form 706 and elect | Fund the trust under the document |
| Shelters post-death appreciation | No, DSUE is a frozen dollar figure | Yes |
| Indexed for inflation | No | Growth stays outside the estate |
| Second basis step-up at survivor’s death | Yes, assets held outright | No, for trust assets |
| Controls who inherits after the survivor | No | Yes |
| Survives the survivor’s remarriage | Only the last deceased spouse’s DSUE counts | Yes |
| Carries the GST exemption | No | Yes, if allocated |
Portability Versus the GST Exemption
Here is the boundary that catches even careful families: the generation-skipping transfer tax exemption is not portable. The DSUE amount applies to estate and gift tax. It does not apply to the GST tax, which is a separate tax on transfers that skip a generation — typically to grandchildren or to trusts for their benefit.
The GST exemption is equal in amount to the basic exclusion amount, but it must be allocated, and it dies with the first spouse if unused. A family that intends to benefit grandchildren, or that has a dynasty-style trust, cannot rely on portability to carry the GST exemption forward. It has to be allocated on the first spouse’s return, which is one more reason to file. The mechanics are set out at the generation-skipping transfer tax.
State estate and inheritance taxes are a separate boundary again. A number of states impose their own estate tax at exclusion levels far below the federal figure, and most of those states do not offer a state-level portability election. Maryland and Hawaii are the well-known exceptions that do. If the household lives in or owns real property in a state with its own estate tax, the state analysis has to be run separately by a CPA or attorney licensed there.
The Form, the Deadline, and the Late-Election Relief
Portability is elected on Form 706, United States Estate (and Generation-Skipping Transfer) Tax Return. There is no shorter form and no box to check elsewhere. The election is made by filing a complete and properly prepared 706 within the deadline; filing the return and not affirmatively opting out is what makes the election.
The deadline is nine months after the date of death, with an automatic six-month extension available by filing Form 4768 — a total of fifteen months. That is the timeline in every ordinary case.
The relief valve matters enormously for widows and widowers who never filed because no tax was due. Revenue Procedure 2022-32 provides a simplified method to make a late portability election for estates that were not otherwise required to file a return, extended to five years after the date of death. It replaced the two-year window in Revenue Procedure 2017-34. The return must state at the top that it is filed pursuant to that revenue procedure. Beyond five years, the only route is a private letter ruling, which is expensive. As of 2026 this is the governing procedure; confirm it has not been superseded before relying on it, and have a CPA or estate attorney prepare the return.
One practical note on valuation. A Form 706 requires reporting the value of every asset, including life insurance. The carrier’s statement of value comes on IRS Form 712, which the executor requests from the insurance company. Order it early; carriers routinely take weeks to produce it.
Where Life Insurance Fits
Life insurance interacts with portability in three concrete ways.
Inclusion. A death benefit is included in the insured’s gross estate if the insured held any incident of ownership at death — the right to change the beneficiary, borrow against the policy, surrender it, or assign it. That rule is Internal Revenue Code section 2042. It surprises people because the money is income tax free under section 101(a) but still counts in the estate. At a $15 million exclusion, most households will not care. At a lower exclusion, they would.
The three-year rule. Transferring a policy out of your name does not immediately remove it from your estate. Under section 2035, a policy transferred within three years of death is pulled back into the gross estate. This is the reason trusts are usually created to buy new coverage rather than to receive existing coverage.
The trust that no longer has a job. Many irrevocable life insurance trusts were funded in the 1990s and 2000s to solve an estate tax problem that a $15 million exclusion has now removed for that family. The premiums, though, keep coming, often into a policy whose illustration has not held up. That is a genuine decision point — whether to keep funding it, reduce the death benefit, surrender it, or have the trustee explore a sale — and it is covered at trust-owned life insurance and, for the specific case of an exclusion change, at what an exemption change means for an existing policy.
Be clear on the boundary: portability itself has no effect on whether a policy can be sold or what it is worth. Secondary market value depends on the insured’s age and health, the death benefit, and the cost of keeping the policy in force. Portability changes only whether the death benefit is taxed in an estate. If a trustee is weighing what to do with a policy the trust no longer needs, that is a fiduciary decision requiring an independent valuation and the beneficiaries’ informed consent, and it should be made with counsel.
The Short Version for a Surviving Spouse
If your spouse has died recently, four things are worth knowing this month.
One: filing Form 706 to elect portability is worth discussing with a CPA even if the estate is nowhere near the exclusion, because the cost is a return preparation fee and the benefit is an option you cannot recreate later.
Two: the deadline is nine months, extendable to fifteen, with a five-year simplified relief window under Revenue Procedure 2022-32 for estates not otherwise required to file. Put those dates on a calendar now.
Three: the DSUE amount does not grow. It is a fixed dollar number computed on the first spouse’s return, and it is not indexed for inflation.
Four: remarriage can wipe out an inherited DSUE if the new spouse dies first, because only the last deceased spouse’s DSUE is available.
Pine Lake Legacy provides education and a free policy review only, and nothing here is legal or tax advice. Portability elections and estate returns belong to your CPA and your estate attorney. If part of the picture is an in-force life insurance policy — a trust-owned policy, a policy inherited from a spouse, or a policy whose premiums no longer make sense — we will review it at no cost and with no obligation. Send the policy cover page or call (732) 978-9575.
Frequently Asked Questions
Do we have to file Form 706 if no estate tax is owed?
Not to pay tax, but yes if you want portability. The deceased spousal unused exclusion is elected only by filing a complete Form 706 within nine months of death, extendable six months. Estates not otherwise required to file may use the simplified late-election relief in Revenue Procedure 2022-32 for up to five years after death.
Does the DSUE amount grow with inflation?
No. The transferred amount is fixed in dollars as computed on the first spouse’s return and does not increase afterward, even though the surviving spouse’s own basic exclusion is indexed annually. In a long widowhood with appreciating assets, that difference is the strongest argument for using a credit shelter trust instead.
What happens to portability if the surviving spouse remarries?
A surviving spouse may use the DSUE only of their most recent deceased spouse. Remarrying does not itself destroy the earlier DSUE, but if the new spouse also dies first, that later spouse’s DSUE replaces it. Any amount not already used through gifts before that point is lost. Discuss the timing with your CPA.
Is portability available for state estate taxes?
Rarely. Several states impose their own estate or inheritance tax at exclusion levels well below the federal amount, and most provide no state-level portability election. Maryland and Hawaii are recognized exceptions that do allow one. If you own property in a state with its own estate tax, have that analysis run by counsel licensed there.
Does portability affect life insurance proceeds?
Only in the estate tax calculation. A death benefit is generally free of income tax under section 101(a) regardless, but it is included in the insured’s gross estate if the insured held incidents of ownership at death, under section 2042. Portability changes the size of the exclusion applied against that estate, nothing else.
Should we still keep an old life insurance trust now that exclusions are high?
That is a real question and the answer is not automatic. The trust may still serve creditor protection, blended-family or liquidity purposes. But if it exists solely to solve an estate tax that no longer applies to your family, the trustee should evaluate whether continued premiums make sense, with counsel and with a current in-force illustration in hand.
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Related Reading
- Estate Tax Exemption Change Policy
- What Is Trust Owned Life Insurance
- Stepped Up Basis Misconception
- What Is The Generation Skipping Transfer Tax
- What Is The Gift Tax Annual Exclusion
- What Is Irs Form 712
- Estate Plan Changed
- What Is Probate
Pine Lake Legacy does not purchase life insurance policies and does not provide legal, tax, or investment advice. Information provided is for educational purposes only. Eligibility for any option, including life settlements, is not guaranteed and depends on individual circumstances, policy terms, underwriting, and market conditions. Consult independent legal, tax, or financial professionals before making decisions regarding a life insurance policy.