Estate Tax Portability Election: How to Preserve the First Spouse’s Exemption

The estate tax portability election is made by filing a complete Form 706 (United States Estate Tax Return) for the deceased spouse’s estate and electing portability on the return. The election is the default if Form 706 is filed and the executor does not affirmatively opt out by checking the appropriate box. The filing deadline is nine months after the date of death under §6075(a), with an automatic six-month extension available by filing Form 4768. The total window is 15 months from death. Missing this deadline without qualifying for Rev. Proc. 2022-32 late-election relief generally means the portability benefit is lost permanently, although a private letter ruling remains available for estates with sufficient justification and the capacity to pay PLR fees.

Form 706 must include the executor’s signature, identification of the gross estate’s assets and values, calculation of the deceased’s adjusted taxable gifts, computation of the taxable estate after deductions, and the resulting Deceased Spouse’s Unused Exclusion (DSUE) amount. The DSUE is the deceased’s basic exclusion amount ($15 million in 2026) minus the amount used by the deceased for taxable gifts during life and the amount used against the taxable estate at death. For most spouses who leave everything to the surviving spouse (using the unlimited marital deduction under §2056), the entire $15 million exclusion remains unused and transfers as DSUE.

The estate tax portability election locks in the DSUE based on the law at the time of the first spouse’s death. The surviving spouse then has the DSUE plus their own basic exclusion available at the second death. If the federal exemption changes between the first and second deaths (which it has historically and will under the 2025 sunset of TCJA absent congressional action), the DSUE remains at the amount established under the law at the first death.

Form 706 for portability-only filings (estates below the federal filing threshold) qualifies for simplified valuation rules under Rev. Proc. 2017-34 and subsequent guidance. The executor does not need formal appraisals for every asset; reasonable valuation methods are acceptable for the portability election. This significantly reduces the cost of filing for non-taxable estates. For estates required to file Form 706 for estate tax purposes (above the threshold), full appraisal documentation is needed under standard valuation rules.

Concrete timeline example: spouse dies January 15, 2026. The nine-month deadline is October 15, 2026. The executor files Form 4768 by October 15 to obtain the six-month extension, pushing the deadline to April 15, 2027. The completed Form 706 with the estate tax portability election is filed by April 15, 2027. The DSUE is established at that filing and becomes available to the surviving spouse for use at their later death. The Form 4768 extension is automatic; no IRS approval is required as long as the form is filed before the original nine-month deadline. Missing the original nine-month deadline does not automatically forfeit the election if Rev. Proc. 2022-32 relief applies, but the cleanest path is to file the Form 4768 timely and use the full 15-month window for Form 706 preparation.

What happens if the deadline is missed: the election fails under the standard rules, but Rev. Proc. 2022-32 provides automatic late-election relief up to five years after death for estates that were not otherwise required to file Form 706. The executor (or the surviving spouse, after the executor’s appointment terminates) can file a Form 706 within five years of death and capture the portability election retroactively. This is one of the most useful pieces of IRS guidance for estate planning in the past decade.

Beyond five years, the relief requires a private letter ruling under Rev. Proc. 2017-34. The PLR process is more expensive and slower (current user fees plus professional fees can run $20,000 to $40,000, with 12 to 18 month processing times) but works for estates significantly past the five-year mark. The Reed Corporation has handled PLR requests for portability elections 10 or more years past the original deadline with success in most cases.

The estate tax portability election does not transfer the GST tax exemption. The generation-skipping transfer tax exemption is the same dollar amount as the estate tax exemption ($15 million in 2026) but each spouse’s GST exemption must be used by them. Unused GST exemption is lost at death. For HNW clients with potential GST exposure (transfers to grandchildren or younger generations), traditional credit-shelter trust planning at the first death still has value to use the first spouse’s GST exemption.

The Reed Corporation files Form 706 for portability elections for clients across NYC and nationwide whenever the surviving spouse’s projected estate might benefit from the DSUE. Even for clients well below the federal exemption, we typically recommend the filing as cheap insurance against future appreciation, future exemption changes, or future events that grow the surviving spouse’s estate. The estate tax portability election preserves optionality for less than the cost of a basic estate plan, and the value of the preserved DSUE can run into millions for the next generation.

One nuance worth flagging: the estate tax portability election is technically an election, which means it can be affirmatively opted out of. There are limited situations where an executor might choose not to elect portability, such as when an opt-out preserves audit privacy for non-portability filings or when the family has structured around credit-shelter trust planning and does not need the federal portability benefit. These situations are rare. For nearly all surviving spouses below the federal estate tax threshold, the election is the right default. The opt-out is generally a mistake in any case where the surviving spouse’s projected estate has even a small chance of exceeding their own exclusion at death.

Form 706 preparation costs for portability-only filings have come down meaningfully since Rev. Proc. 2017-34 simplified the valuation requirements. A typical non-taxable estate portability filing now runs $5,000 to $15,000 in professional fees, down from $15,000 to $40,000 under the prior full-appraisal regime. The simplified valuation lets the executor estimate fair market value reasonably without obtaining formal appraisals for every asset. For estates above the filing threshold or with complex assets, formal appraisals are still needed and costs increase so. The cost reduction has made portability filings accessible for smaller estates that would have skipped them under the older rules.

Rev. Proc. 2022-32 (effective July 8, 2022) extended the period for late portability elections to five years after the date of death for estates that were not otherwise required to file Form 706. The relief is automatic and does not require a private letter ruling, which makes it dramatically cheaper and faster than the prior PLR-only path under Rev. Proc. 2017-34. For most missed elections in estates below the federal filing threshold, Rev. Proc. 2022-32 is the operative authority for capturing the estate tax portability election after the deadline.

The conditions for relief: the decedent must have been a U.S. citizen or resident at death, the estate must not have been required to file Form 706 (the gross estate plus adjusted taxable gifts must have been below the filing threshold in the year of death), no Form 706 was previously filed, and the return is filed within five years of the date of death. If all conditions are met, the executor files a complete Form 706 with the standard portability election checked, and the filing is treated as timely.

Form 706 for a late portability election requires the same content as a timely Form 706. The estate’s assets must be identified and valued, deductions claimed, taxable estate calculated, DSUE computed. The simplified valuation rules under Rev. Proc. 2017-34 apply, which reduces the appraisal burden for non-taxable estates. Most late portability filings can use the executor’s reasonable estimates of fair market value rather than formal appraisals, although better documentation is always preferable.

Concrete example: spouse dies June 1, 2022. The original nine-month deadline was March 1, 2023, with extension to September 1, 2023. The estate was below the filing threshold and no Form 706 was filed. The surviving spouse remarries (which does not affect prior DSUE under the last-deceased-spouse rule), then unexpectedly inherits significant assets in 2025 that grow the projected estate. The advisor identifies the missed portability election in 2026. Under Rev. Proc. 2022-32, the executor can file Form 706 retroactively any time before June 1, 2027 (five years after death) and capture the DSUE. The DSUE captured through the late filing is computed under the law in effect at the original date of death (in 2022, the basic exclusion was $15 million), not under the later 2026 law.

The estate tax portability election under late relief is just as valid as a timely election. The DSUE amount is calculated based on the deceased’s exclusion at the time of the original death, not at the time of the late filing. If the federal exemption was $15 million in 2022 (the year of the example death), the DSUE is computed under that exemption, not under the higher 2026 amount of $15 million. The locked-in DSUE moves forward to the surviving spouse for use at their later death.

Five years is a long window but not infinite. Estates that miss the five-year mark must pursue a private letter ruling under the older Rev. Proc. 2017-34 framework, which provides discretionary relief based on facts and circumstances. The PLR process requires submission of a formal request, payment of the user fee (currently $13,200 for portability rulings), and waiting 12 to 18 months for the IRS to issue the ruling. Success rates are high for well-documented requests but the cost and delay are substantial.

The Reed Corporation has handled both automatic late elections under Rev. Proc. 2022-32 and PLR requests under Rev. Proc. 2017-34 for clients whose first-spouse death predated the relief. The automatic relief is dramatically simpler and cheaper, so we encourage clients to identify missed elections as early as possible and file under the automatic relief while the window remains open. Clients who discover the issue close to the five-year deadline often have just enough time to gather valuation documentation and file before relief is lost.

Common scenarios where late elections become necessary: blended families where the second spouse’s estate grows unexpectedly, business sales after the first death that produce large liquidity events, inheritance from a parent or other relative that swells the surviving spouse’s estate, and federal exemption changes that pull the surviving spouse’s estate above the available exclusion. Any of these can convert a previously inconsequential first-death filing into a critical DSUE recovery exercise.

The cost-benefit math for late portability elections is generally compelling. The cost of filing Form 706 under the simplified rules is typically $5,000 to $25,000 in professional fees, plus minimal IRS processing. The potential benefit is the federal estate tax savings at 40 percent on the DSUE amount, which for a $5 million DSUE is $2 million of avoidable tax. The estate tax portability election under late relief is one of the highest-ROI planning moves available for surviving spouses whose first-death filing was missed.

We have completed late portability filings for clients ranging from spouses who missed the deadline by months to spouses who discovered the issue four years after the first death. In each case, the filing required reconstructing the deceased’s asset profile at the date of death, obtaining valuation evidence for major assets, and preparing a complete Form 706 even though no tax was owed. The reconstruction is harder the longer the gap between death and filing, but it remains feasible for most estates within the five-year window. The IRS does not require perfect reconstruction; reasonable estimates supported by available documentation suffice for the simplified valuation regime.

One additional point on the Rev. Proc. 2022-32 framework: the relief is specifically limited to estates that were not required to file Form 706 in the first place. For estates that were required to file but did not (those above the federal threshold at the time of death), Rev. Proc. 2022-32 does not apply. These estates must seek discretionary relief through the PLR process under Rev. Proc. 2017-34 and face a higher hurdle. Estates that were borderline (close to the filing threshold at the time of death) need careful analysis to determine which relief framework applies. The Reed Corporation walks through this analysis with every client considering a late portability filing to confirm the right procedural path before incurring preparation costs.

The Deceased Spouse’s Unused Exclusion (DSUE) amount is the portion of the first deceased spouse’s basic exclusion amount that was not used by that spouse during life or at death. It is the dollar amount that transfers to the surviving spouse via the estate tax portability election. The calculation under §2010(c)(4) is: DSUE = the basic exclusion amount applicable to the deceased spouse, minus the amount used by the deceased for taxable gifts during life, minus the amount used against the taxable estate at death. The DSUE concept replaces the older bypass trust mechanism for preserving the first spouse’s exemption, and it does so through a much simpler structure that requires only a one-time filing rather than ongoing trust administration.

For most spouses who leave everything to the surviving spouse, the DSUE equals the full exclusion amount. The unlimited marital deduction under §2056 reduces the taxable estate to zero, no exclusion is consumed at death, and assuming no taxable gifts during life, the entire exclusion remains unused. For 2026 decedents, this means a DSUE of $15 million transfers to the surviving spouse.

Concrete example with lifetime gifts: spouse dies in 2026 having made $4 million of lifetime taxable gifts (above the annual exclusion amounts) and leaving $2 million directly to children (using $2 million of estate exclusion) plus the remainder to the surviving spouse (covered by marital deduction). Calculation: basic exclusion $15 million minus $4 million lifetime gifts minus $2 million estate transfers = $7.99 million DSUE. This $7.99 million transfers to the surviving spouse via the estate tax portability election. The lifetime gifts are reported on Form 709 in the years they were made, and the prior gift history must be reconstructed on Schedule G of Form 706 to compute the DSUE correctly. Executors filing Form 706 for portability often need to gather decades of Form 709 records for the deceased spouse, which can be a significant administrative effort if the records were not maintained.

The DSUE is fixed at the dollar amount established at the first spouse’s death under the law at that time. Subsequent changes to the federal exemption do not increase the DSUE. If the exclusion was $15 million in 2026 and Congress later raises it to $20 million, the DSUE from the 2026 death stays at $15 million. Conversely, if Congress lowers the exemption (which it is scheduled to do at 2034 (extended by the One Big Beautiful Bill Act from the original 2025 sunset) under TCJA sunset), the DSUE established at the higher pre-sunset amount may still be useful even after the exemption drops.

The estate tax portability election captures DSUE that is then used in addition to the surviving spouse’s own basic exclusion at the second death. If the first spouse died in 2026 with a $15 million DSUE, and the surviving spouse dies in 2030 when the basic exclusion has fallen to $7 million (post-sunset), the surviving spouse has $7 million own exclusion plus $15 million DSUE = $20.99 million combined. This is one of the most important features of portability: it locks in the higher exclusion of the first death even if the exemption falls later.

The last-deceased-spouse rule under §2010(c)(4)(B) limits portability to DSUE from the most recently deceased spouse. If the surviving spouse remarries and the new spouse dies, the DSUE from the prior spouse is replaced by the DSUE from the most recent spouse. The surviving spouse cannot stack DSUEs from multiple prior deceased spouses. This rule was designed to prevent abuse through serial marriages to terminally ill spouses, although it occasionally produces hard outcomes for survivors who remarry happily and lose meaningful DSUE from the first spouse.

The DSUE applies only to estate tax, not to generation-skipping transfer (GST) tax. The GST exemption is the same dollar amount as the estate tax exemption but is not portable. Each spouse’s GST exemption must be used by them or it is lost. The estate tax portability election does not move GST exemption. For HNW clients with grandchildren or other skip-generation beneficiaries, the loss of the first spouse’s GST exemption can be significant and is one of the central reasons to consider credit-shelter trust planning alongside (or instead of) reliance on portability.

DSUE can be used by the surviving spouse for both lifetime taxable gifts (ahead of the surviving spouse’s own exclusion) and for the taxable estate at the surviving spouse’s death. If the surviving spouse makes a large taxable gift during their remaining life using DSUE, the DSUE is consumed and reduces what remains for use at the second death. This ordering matters for planning purposes, especially when DSUE is larger than the surviving spouse’s own projected need at death.

The Reed Corporation computes DSUE for every client filing Form 706 with a portability election, and we track DSUE positions for surviving spouses across their post-death planning. The estate tax portability election creates a long-term tax attribute that needs to be monitored, used strategically during the surviving spouse’s remaining life, and documented carefully for use at the second death. Surviving spouses with substantial DSUE often benefit from making lifetime taxable gifts to lock in the DSUE-based exclusion against the gift while the law is favorable, particularly given the scheduled 2026 sunset of the high TCJA exemptions.

An important Treasury position to know: the anti-clawback regulations under Treas. Reg. §20.2010-1(c) confirm that DSUE established under the higher pre-sunset exemption (currently $15 million) is preserved even after the exemption falls. If the exemption drops back to roughly $7 million in 2026, a surviving spouse with $15 million of DSUE from a pre-sunset death keeps that DSUE amount. This is a significant protection and means that surviving spouses with first-death dates in the high-exemption window have meaningful planning value to capture before the sunset. The Reed Corporation has been advising clients to file portability elections promptly during the 2018–2034 high-exemption window to lock in maximum DSUE, since the same first-death event in 2026 would generate roughly half the DSUE under the lower post-sunset exemption. Timing matters not just for the late-election deadline but for the value of the DSUE captured.

The estate tax portability election and credit-shelter trust planning are two paths to the same general goal: preserving the first spouse’s exclusion for use at the second death. They have different mechanics, different tax consequences, and different administrative burdens. The choice between them is one of the central decisions in modern estate planning for married couples, and it depends on the client’s asset base, projected appreciation, GST exposure, and tolerance for structural complexity. The 2010 portability legislation (made permanent in 2012) was Congress’s response to decades of complex bypass trust planning that essentially forced couples into trust structures purely for federal estate tax reasons. Portability now provides a simpler default and credit-shelter trusts remain available for situations where their specific benefits justify the added complexity.

Credit-shelter trust planning (also called bypass trust planning or A/B trust planning) funds a trust at the first death with the first spouse’s exclusion amount. The trust holds the assets outside the surviving spouse’s estate, allowing the appreciation to compound outside the federal estate tax base. The trust typically benefits the surviving spouse during life (income distributions, principal access for health and welfare needs) and then passes to children or other beneficiaries at the surviving spouse’s death. The trust structure was the dominant approach for married-couple estate planning from the 1980s through 2010, when portability was introduced as a simpler alternative. Many existing estate plans still use credit-shelter structures and need to be reviewed against current law to determine whether the structure still produces the best total tax outcome or whether modernizing to a portability-based approach would be more efficient.

Portability planning leaves everything to the surviving spouse outright at the first death and relies on the estate tax portability election to preserve the first spouse’s unused exclusion. The surviving spouse owns the assets outright, has full flexibility over them during life, and uses the combined DSUE plus their own exclusion at the second death. This structure is simpler administratively (no trust to manage during the surviving spouse’s life) but does not protect future appreciation from estate tax exposure. The simplicity is genuinely valuable for families that do not need ongoing trust governance. Probate is avoided through revocable trust ownership or transfer-on-death designations, and the surviving spouse retains full discretion over the asset base without trustee oversight or fiduciary duties to other beneficiaries.

Concrete comparison: couple with $20 million estate. First spouse dies in 2026 leaving everything to surviving spouse. Under portability, surviving spouse has $20 million plus full $15 million DSUE. Over the next 20 years, the assets grow to $40 million. At second death, surviving spouse has $40 million estate and $30 million combined exclusion (own plus DSUE, assuming exemption stays at $15 million). Estate tax exposure: $12.02 million × 40 percent = $4.8 million federal estate tax.

Under credit-shelter planning, $15 million goes into the trust at the first death and $6.01 million goes outright to surviving spouse (covered by marital deduction). Over 20 years, the trust grows to $28 million and the outright assets grow to $12 million. At second death, the trust is outside the estate ($28 million sheltered). The surviving spouse’s estate is $12 million, covered by their own $15 million exclusion. Federal estate tax exposure: zero.

The credit-shelter trust saves $4.8 million in federal estate tax in this example by capturing future appreciation outside the surviving spouse’s estate. The cost is the administrative complexity of the trust during the surviving spouse’s life, the loss of step-up at the second death on the trust assets, and the legal fees for trust drafting and administration. For HNW clients with substantial projected appreciation, the trade-off is generally worth it. For clients below the federal exemption with modest projected appreciation, portability is simpler and the savings differential is smaller.

GST exemption is the wild card. Credit-shelter trusts can be designed to use the first spouse’s GST exemption, allowing transfers to grandchildren or later generations to be sheltered from GST tax. The estate tax portability election does not move GST exemption, so the first spouse’s $15 million GST exemption is lost at death if not used during life or at death. For families with intergenerational wealth transfer goals, the credit-shelter trust often wins on GST grounds alone.

State estate tax is another wild card. New York imposes a state estate tax with a $7.16 million exemption in 2026 and no portability mechanism. The first spouse’s $7.16 million New York exemption is lost at death unless captured by a credit-shelter trust funded at the first death. For New York couples and couples in other states with separate estate taxes, the credit-shelter structure can preserve state-level exemption that portability cannot. The federal estate tax portability election is necessary but not sufficient for couples in state-tax states.

The Reed Corporation models both portability and credit-shelter structures for clients and selects the one that produces the better total tax outcome across federal estate tax, state estate tax, GST tax, income tax (including step-up considerations), and administrative cost. For most NYC-area HNW clients above $10 million estate value, some form of credit-shelter planning continues to add value alongside the federal portability election. For couples below the federal threshold, portability often suffices and credit-shelter trusts add complexity without commensurate benefit. The estate tax portability election is the default starting point, and credit-shelter trusts are added when the specific situation justifies them.

A hybrid approach has emerged as the most common modern structure for HNW couples: a disclaimer trust funded only if the surviving spouse affirmatively disclaims a portion of the inheritance into the trust. The first spouse’s estate plan provides for everything to pass to the surviving spouse outright, with a contingent disclaimer trust that the survivor can fund by executing a qualified disclaimer under §2518 within nine months of death. This structure lets the surviving spouse decide at the time of the first death whether to fund the credit-shelter trust (capturing future appreciation and GST exemption) or take everything outright and rely on portability. The decision can be made with current information about asset values, projected appreciation, expected federal exemption changes, and the surviving spouse’s overall situation. The disclaimer trust adds modest drafting complexity but provides flexibility that the rigid choice between portability and credit-shelter trusts does not.

The estate tax portability election is governed by the last-deceased-spouse rule under §2010(c)(4)(B). The surviving spouse can only use the DSUE of the last deceased spouse. If the surviving spouse remarries and the new spouse dies, the DSUE from the first spouse is replaced by the DSUE from the most recently deceased spouse. This is one of the central limitations of portability and produces some counterintuitive results for surviving spouses who remarry. The rule was designed to prevent abuse through serial marriages targeted at accumulating DSUE, but it also catches sympathetic cases where a surviving spouse loses valuable DSUE through a happy second marriage that ends in the second spouse’s death.

Concrete example: Spouse A dies in 2026, leaving the surviving spouse with $15 million in DSUE through the estate tax portability election. The surviving spouse remarries Spouse B in 2028. Spouse B dies in 2030 with a small estate and $2 million of DSUE (because Spouse B used a portion of their exclusion during life or at death). The surviving spouse’s DSUE is now $2 million from Spouse B, not $15 million from Spouse A. The $11.99 million of additional DSUE that came from Spouse A is lost. At 40 percent federal estate tax on the lost DSUE, the family forfeits potential estate tax savings of roughly $4.8 million from the remarriage and second-spouse death sequence. The math is unforgiving and the rule applies regardless of the length of the second marriage.

The rule applies even if the second marriage is short or if Spouse B’s DSUE is meaningfully smaller than Spouse A’s. The most recent deceased spouse’s DSUE controls. This produces hard outcomes for surviving spouses who remarry and outlive a second spouse with limited DSUE to transfer. Planning options to preserve DSUE from the first spouse include making lifetime taxable gifts using the existing DSUE before remarrying or before the new spouse’s death.

The estate tax portability election from the first spouse can be used during the surviving spouse’s lifetime through taxable gifts. If the surviving spouse makes a $15 million taxable gift to children using the first spouse’s DSUE, the gift consumes the DSUE and reduces the surviving spouse’s future estate exposure. This is a permanent use of the exclusion: the gift is sheltered, the children receive the assets, and the surviving spouse’s future estate is reduced by the gift amount. If the surviving spouse later remarries and the new spouse dies, the lifetime use of the prior DSUE is preserved because it was used before the second spouse’s death.

This planning move is one of the central reasons HNW surviving spouses often make large gifts soon after the first spouse’s death, especially when remarriage is contemplated or when the federal exemption is scheduled to decrease. The current law were extended through 2034 by the One Big Beautiful Bill Act (dropping the exemption from $15 million to roughly $7 million in 2026 absent congressional action) makes use-it-or-lose-it gifts particularly relevant. Surviving spouses with large DSUE positions should consider lifetime gifts to lock in the higher exclusion before scheduled changes.

Divorce does not affect the estate tax portability election in the same way as remarriage. If the surviving spouse divorces a second spouse and the second spouse is later deceased, the second spouse is not a deceased spouse of the surviving spouse for §2010(c)(4)(B) purposes if they were not married at the time of death. The DSUE from the first marriage continues to apply because the second spouse never became a deceased spouse of the surviving spouse during the second marriage. This is a technical interpretation but it has been confirmed by the IRS in regulations.

The estate tax portability election from a prior spouse can also be lost through use during the surviving spouse’s life. Lifetime taxable gifts ordered against DSUE first under the §2010(c)(2) ordering rule, then against the surviving spouse’s own exclusion. So a surviving spouse making lifetime taxable gifts after the first spouse’s death uses up the DSUE first, which fits the pattern of locking in DSUE through gifts before remarriage.

Planning for blended families requires careful coordination of the estate tax portability election with the surviving spouse’s overall estate plan. Surviving spouses with significant DSUE who remarry should consider prenuptial agreements that address the disposition of the original family’s assets, lifetime gifting strategies to use DSUE before the second spouse’s potential death, and trust structures that preserve assets for the original family’s beneficiaries. The Reed Corporation works with attorneys and clients to model the gift, trust, and beneficiary structures that preserve maximum value across both marriages.

The bottom line on the estate tax portability election and remarriage: DSUE is fragile. It can be lost by the death of a second spouse with smaller DSUE, by the death of a second spouse with zero DSUE (someone who used their entire exclusion during life), or by changes in tax law between marriages. Locking in DSUE through lifetime gifts is the most reliable protection. For surviving spouses who do not contemplate large lifetime gifts, the estate tax portability election still provides meaningful protection as long as the second marriage’s spouse maintains a substantial unused exclusion at their later death. The risk-reward analysis depends on the specific blended-family situation.

One final point: the last-deceased-spouse rule applies on a moment-of-the-most-recent-spouse-death basis. The surviving spouse’s available DSUE is determined at any given moment by reference to the DSUE of the most recently deceased spouse at that moment. If the surviving spouse is currently unmarried, the DSUE is from the last deceased spouse. If the surviving spouse remarries and the new spouse is alive, the surviving spouse retains the DSUE from the prior deceased spouse until the new spouse dies. This timing nuance affects gift planning during the second marriage. A surviving spouse who remarries but wants to preserve DSUE from the first spouse should consider making lifetime taxable gifts using the original DSUE before the second spouse’s death, while the original DSUE is still the controlling DSUE under the §2010(c)(4)(B) ordering. Once the second spouse dies, the DSUE picture changes regardless of how much DSUE remained at the moment before death.