Estate Tax Portability: How to Preserve a Spouse's Unused Exclusion

Federal estate tax portability can let a surviving spouse use a deceased spouse’s unused exclusion for later taxable gifts or at the survivor’s death. It does not happen automatically. The deceased spouse’s executor generally secures it by filing a timely, complete Form 706 and allowing the portability election to take effect.

An estate may owe no federal estate tax and still have a strong reason to file. The decision should be made from a documented projection, not from the comforting but incomplete statement that “the estate is under the limit.”

Portability is an option owned by the first estate, used by the surviving spouse, and preserved through a filing that may be needed decades later.

The short answer

Calendar the ordinary Form 706 due date nine months after death. Decide early whether to request the automatic six-month filing extension on Form 4768. Have an estate-tax professional determine whether the estate is required to file and whether a portability election is advisable. If portability is elected, retain the complete signed return, proof of filing, valuation support, and the final DSUE computation permanently.

Do not assume the five-year simplified relief procedure cures every late filing. Revenue Procedure 2022-32 is limited to qualifying estates that were not otherwise required to file Form 706 and that meet all of its conditions.

What portability actually transfers

Portability concerns the deceased spousal unused exclusion amount, usually shortened to DSUE. When the first spouse’s executor makes a valid election, that DSUE amount can be added to the surviving spouse’s own basic exclusion amount for federal gift and estate tax purposes.

The 2026 Form 706 instructions state that the survivor may apply DSUE to taxable transfers made after the deceased spouse’s death. They also state that DSUE is used before the survivor’s own basic exclusion amount when the survivor makes a taxable gift.

DSUE is a tax attribute, not cash, an inherited account, or a deduction from income tax. It does not change title to property, direct who inherits, or eliminate the need for trust and beneficiary planning.

The 2026 federal number is $15 million: but that is not the decision

For estates of people who die in 2026, the IRS reports a federal basic exclusion amount of $15,000,000, up from $13,990,000 for 2025 decedents. The relevant amount is tied to the year of death, so a return for an earlier death must use the law and forms applicable to that death.

A high threshold does not make portability irrelevant. The survivor’s assets may grow, inherited assets may appreciate, a closely held company may be sold, insurance may increase the taxable estate, or future law may differ. A survivor may also plan significant lifetime gifts.

Conversely, filing is not automatically cost-effective. A disciplined decision compares filing cost and administrative burden against plausible future exposure. It also considers state estate or inheritance taxes, which have separate thresholds, elections, and rules; a federal portability election does not by itself solve a state tax issue.

The executor makes the election

The surviving spouse cannot simply attach a portability request to her own future return. The election is made on behalf of the deceased spouse’s estate.

The current Form 706 instructions distinguish between an appointed executor who is qualified and acting in the United States and a situation in which no executor has been appointed. Who may file, sign, or opt out can depend on that status and the regulations. Resolve authority before assuming the survivor controls the filing.

This matters when beneficiaries, adult children, or co-executors disagree about the expense. Put the decision, authority, engagement terms, and deadline in writing. Who Has Authority to Act? explains the broader separation between survivor, agent, trustee, and executor roles.

The ordinary deadline is nine months after death

Form 706 is generally due nine months after the date of death. Form 4768 is used to request an automatic six-month extension of time to file. An extension of time to file is not necessarily an extension of time to pay tax; any required payment analysis belongs with the return and extension work.

Do not count months informally and do not wait until the ninth month to hire counsel. Confirm the exact due date, weekend or holiday treatment, delivery method, and extension filing with the preparer.

A simple deadline file should show:

• date of death;
• ordinary Form 706 due date;
• Form 4768 decision date and filing date;
• extended filing date, if applicable;
• responsible executor and preparer;
• valuation and information cutoffs; and
• proof of timely mailing or accepted delivery.

Use The Decision Log Method to preserve those facts.

A timely complete return generally makes the election

The July 2026 Form 706 instructions say that timely filing a complete Form 706 with a DSUE amount is deemed to elect portability when there is a surviving spouse. If the estate files Form 706 but intends not to elect, the executor affirmatively opts out in Part VI.

The election is effective as of the deceased spouse’s date of death. After the filing deadline, the election is generally irrevocable; a timely amended or supplemental return may adjust it before that deadline. This is another reason not to treat a “zero tax” return as a casual formality.

The preparer should use the version of Form 706 and instructions applicable to the decedent and complete the portability computation in Part VI, including Schedule M issues where relevant.

DSUE is not simply $15 million minus the probate estate

The probate inventory is not the federal gross estate, and neither is the checking-account balance. Form 706 reaches property interests included under federal estate-tax rules, which may include jointly held property, life insurance, retirement assets, trusts, business interests, taxable lifetime gifts, and other transfers not controlled by the will.

The Form 706 instructions describe DSUE as the lesser of:

• the basic exclusion amount in effect at the deceased spouse’s death; or
• the deceased spouse’s applicable exclusion amount minus the taxable estate plus adjusted taxable gifts figured on the return (Part II, line 5), subject to the statutory computation.

That description cannot be safely reduced to a household arithmetic shortcut. Prior gifts, gift tax paid, DSUE the deceased spouse may have received, deductions, and return positions can affect the result. Have the preparer show the computation and identify every input.

Inventory before estimating

Build a gross-estate map even when most assets pass directly to the survivor. Gather:

• ownership and beneficiary records for every financial account;
• deeds, title reports, and qualified appraisals for real estate;
• life-insurance policies, incidents of ownership, and death-benefit records;
• retirement and annuity statements;
• trust instruments, amendments, funding records, and powers of appointment;
• business agreements, capitalization tables, financial statements, and appraisal material;
• notes receivable, partnership interests, intellectual property, digital assets, and valuable tangible property;
• debts, administration expenses, charitable transfers, and marital transfers;
• all prior Forms 709 and supporting gift records; and
• any portability return from a spouse who died before this decedent.

Tie each value to a source and valuation date. Valuing Assets at the Date of Death provides a separate evidence workflow.

A portability-only return may have limited valuation relief

The regulations and Form 706 instructions provide a special reporting rule for some estates that are not otherwise required to file and file only to elect portability. Certain property qualifying for the marital or charitable deduction may be reported using good-faith estimates and prescribed value ranges instead of a precise value.

This is not permission to omit the asset search or guess casually. The executor must exercise due diligence, the rule does not cover every asset or every filing purpose, and accurate values may still matter for basis, allocation, state tax, trust funding, family accounting, or a later audit.

Ask the preparer to identify in writing:

• which property qualifies for estimated-value reporting;
• which property still needs a specific appraisal;
• how each estimate was developed;
• whether another election or tax position requires precision; and
• how the estimated property affects the DSUE computation.

Late-election relief has a five-year path for some estates

Revenue Procedure 2022-32 provides a simplified method for certain estates to obtain an extension to elect portability. Among its conditions, the deceased spouse must have died after 2010, been a U.S. citizen or resident at death, and been survived by a spouse. The executor must not have been required to file Form 706 under the normal gross-estate-and-adjusted-taxable-gifts test, and no timely Form 706 may have been filed.

For a qualifying estate, the executor must file a complete and properly prepared Form 706 on or before the fifth anniversary of death and place the prescribed Revenue Procedure 2022-32 statement at the top of the return.

The five years run to the anniversary, not five years after the original nine-month due date. The procedure’s exact language and eligibility conditions matter. A late filer should use the current Form 706 instructions and have a professional confirm that the estate fits within the revenue procedure before relying on it.

When the simplified relief procedure does not apply

Revenue Procedure 2022-32 does not rescue an estate that was actually required to file Form 706 under section 6018. The revenue procedure says the simplified extension is unavailable in that situation because the election deadline is prescribed by statute.

It also does not cover an estate merely because someone now wishes portability had been considered. Citizenship or residency, marital status at death, filing requirement, prior return history, the five-year anniversary, and a complete return all matter.

Some estates outside the simplified method may consider a private-letter-ruling request under the regulatory relief rules, but eligibility, cost, user fees, and timing require specialized advice. It is not a promised second chance. Treat the ordinary deadline as real.

A required-return estate faces a harder deadline

If the gross estate plus adjusted taxable gifts crosses the filing threshold applicable to the year of death, Form 706 is required independently of portability. The simplified late-election relief in Revenue Procedure 2022-32 is not available.

That classification must be made from a complete federal gross-estate analysis. An apparently modest probate estate can coexist with large nonprobate assets, prior taxable gifts, life insurance, or trust interests. Do not decide “not required” from the will or probate petition alone.

See Whether an Estate Tax Return Is Required for the filing-threshold analysis.

Portability does not carry the GST exemption

The generation-skipping transfer tax has its own exemption and allocation rules. Portability transfers DSUE for federal gift and estate tax purposes; it does not port the deceased spouse’s unused GST exemption to the survivor.

Families with dynasty trusts, skip beneficiaries, large insurance trusts, or multigenerational transfers therefore need a separate GST review at the first death. A portability filing is not a substitute for allocating GST exemption or making other time-sensitive elections.

The last-deceased-spouse rule can change the strategy

The survivor generally uses DSUE from the “last deceased spouse.” Remarriage by itself does not replace the prior deceased spouse while the new spouse is alive. But if a later spouse dies, that later spouse may become the last deceased spouse, and unused DSUE from an earlier spouse generally cannot simply be stacked with the later spouse’s DSUE.

The Form 706 instructions explain that a survivor with multiple deceased spouses may use DSUE amounts in succession but may not use the sum of multiple spouses’ DSUE amounts at one time. Lifetime taxable-gift planning can interact with these ordering rules.

This is specialist territory. Before remarriage, substantial gifts, or a new spouse’s declining health, ask estate-tax counsel to model the existing DSUE, possible use during life, and the effect of a later death. Do not make a gift solely to “use portability” without a complete cash-flow, basis, control, creditor, and family analysis.

Portability can be used during life

Once validly elected, DSUE may be available for the survivor’s taxable gifts after the deceased spouse’s death. The rules generally apply DSUE from the last deceased spouse before the survivor’s own basic exclusion amount.

A lifetime use can matter if the survivor expects asset appreciation, plans family transfers, or faces the last-deceased-spouse issue. But using exclusion is not the same as making a wise gift. A gift can surrender control, liquidity, income, basis advantages, or protection from unforeseen care costs.

Any significant transfer should be coordinated among estate counsel, tax counsel, the return preparer, and the investment or business adviser. Record which exclusion the Form 709 reports as used and preserve the portability return with the survivor’s gift-tax file.

The IRS may later examine the first return’s DSUE

The Form 706 instructions warn that when the survivor applies DSUE to a lifetime gift or transfer at death, the IRS may examine the predeceased spouse’s return to verify the allowable amount. The DSUE can be adjusted or eliminated as a result, even though assessment of additional tax against the first estate remains subject to the applicable limitation period.

The practical lesson is not to discard the first return after an ordinary tax-retention period. Preserve permanently:

• the complete signed Form 706 and every schedule;
• the filing receipt, certified-mail record, or approved delivery evidence;
• Form 4768 and proof of filing, if used;
• appraisals and valuation workpapers;
• account statements and ownership evidence;
• Forms 709 and gift files;
• trust, business, insurance, and debt documents;
• correspondence with the IRS;
• amended or supplemental returns; and
• the preparer’s DSUE computation and assumptions.

Keep an encrypted digital copy in a separate location and tell the survivor’s future executor and tax adviser where it is. How to Store Estate Planning Documents gives a custody design.

Do not confuse Form 706 with the estate’s income-tax return

Form 706 is the federal estate and generation-skipping transfer tax return. Form 1041 is generally the income-tax return for an estate or trust. Filing one does not automatically satisfy the other.

Portability also does not determine income-tax basis by itself. The date-of-death valuation work can overlap with basis reporting, but basis rules, community-property treatment, income in respect of a decedent, and later sales require their own analysis. Preserve consistent valuations and explain any legally supportable difference across filings.

State estate taxes require a separate calendar

States may impose estate or inheritance taxes at thresholds far below the federal amount. Some state systems have their own elections, marital-deduction planning, or filing requirements; some do not recognize federal portability in the same way.

Create two lines in the decision memo:

• federal Form 706 requirement and portability decision; and
• every potentially relevant state death-tax return, election, and deadline.

Residence is not the only state connection. Real property, business interests, trusts, prior domicile, and beneficiary location may require review. Use State Taxes Are a Separate Question to build the state list.

Noncitizen and cross-border families need specialist advice

The standard portability discussion assumes a deceased spouse who was a U.S. citizen or resident and a surviving spouse within the federal marital system. The Form 706 instructions state that the executor of a nonresident decedent who was not a U.S. citizen cannot make a portability election. Qualified domestic trust rules can also delay or change DSUE availability when the surviving spouse is not a U.S. citizen.

Do not apply a domestic-spouse checklist to cross-border facts. Citizenship, domicile, treaty coverage, situs assets, prior transfers, QDOT provisions, and foreign tax credits may all matter. Engage counsel who routinely handles international estate tax before a filing or disclaimer deadline passes.

A decision memo should show the forecast

The filing recommendation should be more than “probably worthwhile.” Ask for a written comparison with at least three scenarios:

Scenario	Questions to model
Current values	What is the projected DSUE, survivor’s present estate, and current federal and state exposure?
Growth case	What happens if investments, real estate, insurance, or a business appreciate over the survivor’s planning horizon?
Change case	What happens under plausible gifting, remarriage, relocation, sale, inheritance, or legislative assumptions?

Show the filing and appraisal cost separately from ongoing planning costs. Identify assumptions rather than presenting the projection as a prediction. The goal is to buy or decline an option knowingly.

A hypothetical illustrates the question, not the answer

Suppose a spouse dies in 2026 with assets well below the $15 million basic exclusion, most property passes to the survivor, and no federal estate tax appears due. The survivor already owns substantial assets and expects a business interest and investment portfolio to grow.

The executor may not otherwise be required to file, yet portability could preserve a material DSUE amount. The team still has to inventory the federal gross estate, review prior gifts, value non-marital assets, apply the Form 706 computation, and assess state tax. The result is not automatically “$15 million minus what the family thinks the estate was worth.”

This hypothetical does not prove the election is right. It shows why no-tax-due and no-return-worth-filing are different conclusions.

The first 30-day workflow

1. Identify the executor and the estate-tax decision maker.
2. Calendar the nine-month due date and an earlier extension decision date.
3. Retain an estate-tax preparer with Form 706 portability experience.
4. Order date-of-death account records and start appraisals for hard-to-value assets.
5. Locate every prior Form 709 and any DSUE received by the deceased spouse.
6. Build the federal gross-estate inventory, including nonprobate property.
7. Ask whether any state death-tax filing or election has an earlier deadline.
8. Obtain a written required-return analysis and portability recommendation.
9. Decide whether Form 4768 should be filed.
10. Establish permanent physical and encrypted digital return files.

The sequence protects the deadline while the harder valuation work proceeds.

Questions for the preparer before engagement

• How many portability-only Forms 706 has the preparer completed?
• Who performs and reviews the DSUE computation?
• Which assets need qualified appraisals, and who selects the appraiser?
• Does the estate qualify for the special estimated-value reporting rule?
• What information is still missing from the federal gross-estate inventory?
• Is Form 706 required independently of portability?
• What is the exact ordinary due date, and when will Form 4768 be filed if needed?
• Does Revenue Procedure 2022-32 matter, and does the estate satisfy every condition?
• What state, GST, QDOT, noncitizen, or prior-spouse issues are outside the quoted scope?
• Who will retain the complete filing package and proof of filing?

The engagement letter should identify return preparation, valuation coordination, audit response, amended returns, state filings, and post-filing planning separately. How to Choose an Estate Attorney helps define legal scope and client identity.

Red flags that deserve a second opinion

• “No federal tax is due, so there is nothing to file,” without a portability analysis.
• A DSUE estimate based only on probate assets.
• No request for prior Forms 709 or earlier portability records.
• A promise that five-year relief is available without testing whether the estate was required to file.
• Treating federal portability as a state estate-tax election.
• Saying the deceased spouse’s unused GST exemption will port with DSUE.
• Recommending large gifts without a cash-flow and basis analysis.
• Filing close to the deadline without documented delivery evidence.
• No permanent record-retention plan.
• Cross-border facts handled with a standard domestic checklist.

Frequently asked questions

Is portability automatic between spouses?

No. The deceased spouse’s executor generally must make the election through a timely, complete Form 706. A qualifying late estate may use Revenue Procedure 2022-32, but the survivor cannot simply claim an unpreserved amount years later.

Must an estate file Form 706 when no estate tax is due?

It may need or choose to. A return can be required because the statutory filing test is met even when deductions eliminate tax. A below-threshold estate may voluntarily file to elect portability.

How long does an executor have to elect portability?

The ordinary Form 706 due date is nine months after death, with a possible automatic six-month filing extension requested on Form 4768. For certain estates not otherwise required to file, Revenue Procedure 2022-32 may allow a properly completed portability return on or before the fifth anniversary of death.

Does portability double the survivor’s exclusion?

Not necessarily. It adds the validly computed DSUE amount, which depends on the deceased spouse’s own exclusion use and Form 706 calculation. It is not automatically equal to the full basic exclusion amount.

Does remarriage erase DSUE?

Remarriage alone does not change the identity of the last deceased spouse while the new spouse is alive. The later death of a new spouse can change which DSUE is available. Multiple-spouse and lifetime-gift rules require individualized planning.

Can the IRS revisit DSUE later?

Yes. When the survivor uses DSUE, the IRS may examine the predeceased spouse’s return to verify the amount and can adjust or eliminate the DSUE, subject to the separate rules limiting assessment against the first estate. Preserve the complete file permanently.

Does portability cover state estate tax or GST exemption?

No general assumption is safe. Federal DSUE portability does not port the federal GST exemption, and state death-tax systems must be analyzed separately.

Primary federal sources

• IRS: Instructions for Form 706, revised July 2026
• IRS: Revenue Procedure 2022-32
• IRS: 2026 tax inflation adjustments
• IRS: Portability final regulations
• IRS: About Form 706
• IRS: About Form 4768

Where general guidance ends

This guide cannot determine a filing requirement, compute DSUE, value an estate, establish executor authority, or decide whether a portability election is worth its cost. Those conclusions require the decedent’s year of death, citizenship and residency, marital history, prior gifts, complete asset and deduction records, state connections, and professional review of current law.

What this comes down to

Ask two separate questions before the ordinary deadline: “Must this estate file?” and “Should this estate file to elect portability?” Preserve the answer, the complete return, and its evidence as long as the surviving spouse or her estate may rely on the DSUE.