What Is Estate Tax Portability, and How Do I Claim My Spouse's Unused Exemption?
Last reviewed: July 2026
Estate tax portability lets a surviving spouse use the deceased spouse's unused federal estate exemption. The IRS calls the unused portion the Deceased Spousal Unused Exemption, or DSUE, and it transfers only when the executor of the first spouse's estate files Form 706 and makes the election. With the per-person exemption set at $15 million for 2026, portability is the difference between $15 million sheltered from federal estate tax and a combined $30 million sheltered for the couple.
Key Takeaways
- The federal estate exemption is $15 million per person and $30 million per couple in 2026; portability transfers the deceased spouse's unused amount.
- Portability requires filing Form 706 within nine months of death, with a six-month extension available.
- Late portability elections are allowed up to five years after death under Rev. Proc. 2022-32 for non-filing estates.
- The top federal estate, gift, and GST tax rate stays at 40 percent on amounts above the exemption.
- Maryland levies its own state estate tax at a separate $5 million exemption, and portability does not apply to it.
About the Author: Jeff Judge, CFP®, AEP®, ChFC®, CLU® is Managing Partner of Chesapeake Financial Planners in Forest Hill, Maryland. He has been helping families and business owners in Harford County and the Baltimore metro area work through estate tax portability and lifetime exemption planning since earning his CFP® certification in 2013, by using Chesapeake Financial Planners’ signature process, the R.U.D.D.E.R. method™. Jeff has seen too many widows discover years after the funeral that nobody filed Form 706, and the unused exemption walked out the door alongside the estate attorney's invoice.
What is portability, and what does the DSUE actually transfer?
Portability is a federal election that moves a deceased spouse's unused estate tax exemption to the surviving spouse. Congress introduced it under the Tax Relief Act of 2010 and made it permanent in 2013. Before portability, exemptions died with the spouse; couples relied on credit-shelter trusts (often called bypass or A/B trusts) just to capture both exemptions. Now the executor can simply elect portability on Form 706, and the unused amount, the DSUE, attaches to the surviving spouse's own exemption.
The math is straightforward. If the first spouse to die used $3 million of their $15 million exemption, the remaining $12 million becomes the surviving spouse's DSUE. Add that to the surviving spouse's own $15 million for 2026, and they now hold $27 million of combined federal exemption to use for lifetime gifts or at death. That number stays at $27 million even if the surviving spouse remarries, with one important wrinkle covered below.
One trap matters here: the DSUE is fixed at the date of the first spouse's death. It does not grow with inflation. The surviving spouse's own exemption indexes up over time, but the DSUE does not. A widow who carries a $5 million DSUE from 2018 still has exactly $5 million of DSUE in 2026, regardless of how much the basic exemption has climbed since.
Portability did not eliminate the case for credit-shelter trusts. A trust still wins when the family wants to lock in growth on the deceased spouse's exemption (the DSUE itself does not appreciate), shield assets from creditor or remarriage risk, or control disposition to children from a prior marriage. Portability wins when simplicity, basis step-up, and administrative ease matter more than asset protection.
How do you elect portability after your spouse dies?
The executor of the first-to-die spouse's estate elects portability by filing a complete Form 706, the United States Estate (and Generation-Skipping Transfer) Tax Return. The election happens automatically when a timely Form 706 is filed, unless the executor affirmatively opts out on the return. There is no separate election form and no checkbox; the act of filing 706 (and not opting out) does the work.
Here is where most families get tripped up. Filing Form 706 is not required if the gross estate is under the federal filing threshold. A $5 million estate triggers no federal filing obligation on its own. But to preserve portability, the executor must file Form 706 anyway, on time, and complete enough of the return to identify the DSUE. The IRS calls this a "portability-only return," and it carries the same nine-month filing deadline as a regular estate tax return, with a six-month extension available via Form 4768.
Jeff Judge has watched this exact mistake cost clients seven and eight figures of future tax exposure. Most people assume Form 706 isn't relevant because they're nowhere near the exemption. By the time the family realizes portability was the whole point of filing, the deadline has passed and the estate is in cleanup mode. The fix exists, but it is a fix, not a plan.
A portability-only return is substantially lighter than a full estate tax return. The executor still values the assets, but the IRS does not require formal appraisals on every line item for portability-only filings (the regulations allow a "good faith estimate" for many assets, rounded to the nearest $250,000). Even so, the return is long, the deadlines are strict, and most families benefit from an estate attorney or CPA who handles 706 filings routinely rather than as a one-off.
When does claiming estate tax portability matter most?
Portability matters most when the couple's combined wealth is below one exemption but above half, or when the surviving spouse expects to accumulate wealth through inheritance, business growth, or a windfall after the first spouse dies. Three patterns come up repeatedly with Chesapeake's clients in Harford County and the broader Baltimore metro.
The first pattern is the asymmetric estate. One spouse holds most of the marital assets, often because they were the business owner or the primary saver. If that spouse dies first having used little or none of their exemption, portability captures the full amount and the surviving spouse keeps it available for future planning. Without portability, those millions of exemption simply vanish.
The second pattern is the late-life inheritance. A surviving spouse in their seventies receives a $4 million inheritance from a parent after the first spouse has died. If portability was elected, the surviving spouse uses both exemptions to absorb that inheritance and grow it for the next generation. If portability was not elected, the same $4 million stacks on top of an already-strained personal exemption, and the family could face federal estate tax at a top rate of 40 percent on the excess.
The third pattern is post-loss appreciation. A widow inherits a closely held business worth $8 million at her husband's death; ten years later it is worth $20 million. Without DSUE in hand, she is several million dollars over her own exemption and writing checks to the IRS at 40 cents on the dollar above the threshold. With DSUE, the same growth is fully sheltered.
What are the deadlines for the estate tax portability election?
The standard deadline for filing Form 706 is nine months after the date of death, with an automatic six-month extension available if the executor files Form 4768 on time. That gives the executor up to fifteen months from death to file a complete return and lock in the DSUE.
A late portability election is allowed up to five years from the date of death under Rev. Proc. 2022-32, issued in July 2022. The five-year window applies only to estates that were not otherwise required to file Form 706 (estates under the filing threshold). To use it, the executor files a complete 706, writes "FILED PURSUANT TO REV. PROC. 2022-32 TO ELECT PORTABILITY UNDER §2010(c)(5)(A)" across the top of the return, and submits it before the fifth anniversary of death. The Rev. Proc. replaced the older two-year window that had been in place under Rev. Proc. 2017-34.
If the five-year window is missed, the executor's only remaining option is to request a Private Letter Ruling from the IRS under Treasury Regulation §301.9100-3, which requires showing reasonable cause, the absence of prejudice to the government, and a willingness to pay user fees that currently start in the low five figures. The success rate is reasonable, but the timeline can stretch eighteen months. This is the worst-case path. Filing the original 706 on time is dramatically cheaper.
Two practical points the calendar doesn't capture. First, the nine-month clock starts on the date of death, not the date the executor takes office. Probate delays do not extend the deadline. Second, the surviving spouse's own death freezes the DSUE picture for their estate, so if the surviving spouse dies before the late-portability window closes, the executor of the second estate cannot retroactively file a 706 for the first spouse.
How does portability interact with state estate taxes and the GST exemption?
Federal portability does not transfer to state estate taxes. Maryland is one of the few states with both a state estate tax and an inheritance tax, and the Maryland exemption is $5 million per decedent without any portability provision. A surviving Maryland spouse cannot carry over a deceased spouse's unused state exemption. Couples with combined assets near or above $5 million who live in Maryland still need credit-shelter or QTIP planning at the state level even though the federal side is solved by portability.
Federal portability also does not apply to the generation-skipping transfer (GST) tax exemption, which is also set at $15 million per person in 2026. The GST exemption must be specifically allocated on the estate tax return; it does not move automatically to a surviving spouse. Couples planning legacy gifts to grandchildren or trusts that skip generations need a deliberate GST allocation strategy at the first death.
The R.U.D.D.E.R. Method™ is Chesapeake Financial Planners' six-step planning process: Review and Recognize, Uncover and Understand, Design and Develop, Discuss and Decide, Execute and Empower, and Reassess and Refine. The first three steps land squarely on portability decisions. Review and Recognize identifies the surviving spouse's actual exemption position; Uncover and Understand catalogs the marital assets and the timeline since death; Design and Develop puts the 706 filing on the calendar and decides whether portability or a credit-shelter approach better fits the family.
Related Topics Worth Reading
Estate planning at this level rarely sits alone. Three topics come up alongside the portability conversation, and each deserves its own deeper read.
The first is the role of step-up in basis for inherited assets, which controls how much capital gains tax the surviving spouse owes when they sell what they inherited. The interaction with portability changes the optimal mix of gifts now versus inheritances later. What is step-up in basis, and how are inherited assets taxed?.
The second is charitable strategy. Donor-advised funds, qualified charitable distributions, and private foundations each offer a different lever for reducing the taxable estate while supporting causes the family cares about. Donor-advised fund, private foundation, or QCD: which giving strategy fits me?.
The third is long-term care planning. A $250,000 long-term care event in the surviving spouse's final years can convert exempt assets to taxable estate inclusion in a hurry. Hybrid policies pay a death benefit if care is never used, which preserves the estate's value for heirs even when the policy is never claimed. How Do Hybrid Long Term Care Insurance Policies Work?.
Want to go deeper? Our Busy Professional's Guide to Making Financial Progress walks through this step by step.
Prefer a different starting point? Our What To Do When You Lose a Loved One is worth a look.
Two more deserve a place on the reading list for anyone working through this material: How can a qualified charitable distribution lower my RMD and taxes? and What is the right retirement withdrawal order for your accounts?.
Frequently Asked Questions
Do you have to file Form 706 even if the estate is under the federal exemption?
Yes, the executor must file Form 706 to elect portability even when the gross estate is well under the federal filing threshold. The IRS calls this a portability-only return. Filing is the only mechanism that transfers the DSUE to the surviving spouse, and the executor cannot recreate the election later by amended return.
What happens if you miss the portability filing deadline?
If you miss the standard nine-month deadline or the fifteen-month extended deadline, Rev. Proc. 2022-32 allows estates under the filing threshold to elect portability for up to five years after death. Beyond five years, only a Private Letter Ruling can revive the election, and the user fees plus the timeline make it the worst-case path.
Can portability be lost if the surviving spouse remarries?
Portability is not lost on remarriage itself, but the DSUE from a prior deceased spouse can be replaced. The "last deceased spouse" rule means the DSUE available to a surviving spouse is the unused exemption of their most recent deceased spouse. If a widow remarries and her new husband then dies with little used exemption, his DSUE replaces the first husband's DSUE.
Does portability apply to the generation-skipping transfer (GST) tax exemption?
No, portability applies only to the basic estate and gift tax exemption. The GST exemption, also $15 million per person in 2026, must be allocated specifically on Form 706 and does not transfer automatically to the surviving spouse. Couples doing multigenerational planning need a deliberate GST allocation strategy alongside their portability election.
Can the IRS audit a portability election years later?
Yes, the IRS retains the authority to examine the DSUE amount when the surviving spouse uses it, even after the statute of limitations on the first estate has closed. Valuation errors or missing assets from the original return can come back to reduce the DSUE much later. Detailed documentation of the first estate matters even when no tax was owed at the first death.
Estate tax portability is one of the cleanest planning wins available to married couples and one of the most frequently missed. If you've lost a spouse in the last five years and nobody filed Form 706, the Rev. Proc. 2022-32 window may still be open. If you're planning ahead and want to know whether portability or a credit-shelter trust fits your family better, the Estate Planning Primer for Maryland Families at chesapeakefp.com walks through the decision side by side with the numbers.
Disclosures
The information provided is for educational purposes only and should not be construed as investment advice. Investment strategies should be tailored to individual circumstances, risk tolerance, and goals. Past performance doesn't guarantee future results. Consult with qualified financial professionals regarding your specific situation.
This information is not intended to be a substitute for specific individualized tax, investment or legal advice. We suggest that you discuss your specific situation with a qualified tax, legal or financial advisor.
Advisors associated with Chesapeake Financial Planners may be either (1) LPL Financial Registered Representatives offering securities through LPL Financial, Member FINRA and SIPC, and investment advisor representatives offering investment advice through Great Valley Advisor Group; or (2) solely investment advisor representatives offering investment advice through Great Valley Advisor Group and not affiliated with LPL Financial. Great Valley Advisor Group, and Chesapeake Financial Planners are separate entities from LPL Financial.
