Federal Basic Exclusion • Qualified Disclaimer • Bypass Trust • Noncitizen-Spouse Marital Deduction • QDOT Deferral • Second-Death Inclusion

By Alex Oware, CPA and Tax Attorney

Federal law and published thresholds current through July 23, 2026

Wondering what happens when a U.S. citizen leaves a large estate to a spouse who holds a green card but is not a U.S. citizen? This case study begins with the complete facts and then separates three federal concepts that perform different jobs: the decedent's basic exclusion, a qualified disclaimer, and a Qualified Domestic Trust (QDOT). The exclusion determines how much otherwise taxable property can be sheltered at the first death. A disclaimer determines whether the surviving spouse will own a particular asset. A QDOT provides a marital deduction for property intended for a noncitizen spouse when the estate wants to defer tax on value that is not otherwise sheltered by the decedent's exclusion.

---

Case Study Question

A father dies in 2026 with a $20 million federal gross estate. His wife is a lawful permanent resident of the United States, but she is not a U.S. citizen. The estate plan contains both a disclaimer provision and QDOT language. Which assets can pass without current federal estate tax? Does the first $15 million need to enter a QDOT? Why might the wife disclaim assets into a bypass trust if she still needs financial support? Can a disclaimer trust and a QDOT be used together, and what happens to each category of property when the wife later dies?

---

The Facts, Stated Completely

The following facts and assumptions are used throughout the article so that each conclusion can be understood from the facts stated here:

---

The Taxpayer's Actual Problem to Be Solved

The family is not choosing between a disclaimer and a QDOT as though they are competing versions of the same trust. The family must answer three different questions in the correct order:

1. How much of the estate can the father's own federal exclusion protect from tax at the first death?

2. For the exclusion-funded share, should the wife own the assets outright, or should she receive support through a bypass trust without owning the assets?

3. For the value above the father's available exclusion, should the estate pay current tax, or should the excess pass to a QDOT so the marital deduction can defer that tax?

Only the third question is a QDOT question. The first question is an exclusion question. The second is an ownership, control, and second-death planning question.

One Estate, Three Possible Destinations

---

1. Start With the Estate-Wide Federal Tax Calculation

The $15 million basic exclusion is not a separate pot of property that must be placed into a particular trust. Federal estate tax is computed on the estate as a whole. Form 706 reports the gross estate, subtracts allowable deductions, calculates tentative tax, and then applies the decedent's available credit. Practitioners often say that a trust “uses the exclusion,” but the credit legally offsets the estate-wide tax calculation rather than attaching to a named asset.

For a decedent dying in 2026, the basic exclusion amount is $15,000,000. Under the section 2001 rate table, the corresponding applicable credit amount is $5,945,800. Because the father made no prior taxable gifts in this case study, the full amount is available.

Simplified computation if there is no QDOT deduction

This $2 million is the approximate tax cost of leaving all $20 million in a form that receives no marital deduction. It is not caused by the spouse's green card. It is caused by the estate having $5 million more taxable value than the father's available $15 million exclusion.

---

2. A Green Card Does Not Create the Unlimited Estate-Tax Marital Deduction

A green card can make a person a U.S. resident for many income-tax purposes, but lawful permanent residence is not U.S. citizenship. IRC §2056(d) generally denies the federal estate-tax marital deduction when the surviving spouse is not a U.S. citizen. Therefore, property passing outright to this wife is not automatically deducted from the father's taxable estate.

That does not mean the wife cannot receive property without current estate tax. It means the transfer must be sheltered by a different federal rule. In this case, the father's available exclusion can shelter up to $15 million of outright property. The reason the transfer is tax-free at the first death is the father's applicable credit—not a marital deduction and not the wife's immigration status.

A separate statutory exception may apply if the wife becomes a U.S. citizen before Form 706 is filed and satisfies the continuous-residence rule in IRC §2056(d)(4). This case study assumes that does not occur. An applicable estate-tax treaty could also alter the result, but no treaty benefit is assumed here.

---

3. The First $15 Million Does Not Need a QDOT

The father's full $15 million exclusion is available. Therefore, the estate may place up to $15 million of otherwise taxable property into any legally valid destination without current federal estate tax, subject to the assumptions in this article. The property may pass to the wife outright, to children, or to a nonmarital trust. The exclusion is not limited to transfers to a spouse.

If the wife wants full ownership, unrestricted access, and the ability to sell, gift, consume, or redirect the property, the simplest federal structure is to leave the exclusion-funded share outright to her. No disclaimer is required. No QDOT is required for that share. The tradeoff is that the property becomes hers. Its later value and appreciation may be included in her own gross estate when she dies.

The question is therefore not whether the wife “wants” the $15 million. The question is whether she should own it outright or benefit from it through a trust. A disclaimer trust becomes relevant only if the family prefers benefit without ownership.

---

4. Why the Wife Might Use a Disclaimer Trust

A qualified disclaimer is an irrevocable refusal to accept a property interest. It is not a statement that the wife has no financial need for the property. In a properly drafted estate plan, the wife may disclaim legal ownership, the disclaimed property then passes automatically into a bypass trust, and the trust may still provide income or limited principal support to her.

The disclaimer is the routing mechanism. The bypass trust is the destination. The father's will or revocable trust must already state what happens if the wife disclaims. She cannot sign a disclaimer and then decide where the property should go or rewrite the trust after death.

Why a disclaimer-funded bypass trust may be preferable to outright ownership

• The wife can receive income and limited principal distributions while the trust assets are not owned by her outright.
• The trust assets and their future appreciation can generally remain outside her later gross estate if she holds no general power of appointment or other includible ownership power.
• The trust can preserve the father's remainder plan for children or other beneficiaries and can provide protection against remarriage, creditor claims, incapacity, or asset diversion.
• The family can decide within the federal disclaimer period how much property should pass to the trust after obtaining valuations and evaluating the wife's needs.

Why the wife might decline to use the disclaimer trust

• She wants unrestricted ownership and does not want trustee oversight or distribution standards.
• The projected estate-tax savings are small relative to trust administration cost and complexity.
• The family values a second basis adjustment at her death more than exclusion from her gross estate. Property outside her estate generally does not receive a new basis adjustment merely because she dies.
• The trust terms do not provide adequate access or the required disclaimer and retained-power rules cannot be satisfied.

---

5. A Disclaimer Is Not a Deduction or a Separate Exemption

The disclaimed property remains part of the father's federal gross estate. Form 706 does not contain a “disclaimer deduction” that subtracts the property merely because the wife refused it. Instead, the disclaimer changes who receives the property. If the property passes to a bypass trust rather than to a marital-deduction destination, the trust share is a taxable nonmarital transfer. The father's applicable credit then shelters that transfer to the extent of his available exclusion.

Using the simplified facts, if the wife disclaims $15 million into the bypass trust and the remaining $5 million qualifies for a QDOT deduction, the taxable estate after the QDOT deduction is $15 million. The tentative tax on that amount equals the father's $5,945,800 credit, leaving no current federal estate tax.

Simplified computation with a $15 million bypass share and a $5 million QDOT share

---

6. Requirements for the Wife's Disclaimer to Be Qualified

IRC §2518 imposes strict requirements. A federal qualified disclaimer must be an irrevocable and unqualified refusal, be in writing, identify the disclaimed interest, be delivered to the proper person within nine months, occur before the wife accepts the property or any benefit from it, and cause the property to pass without direction by her.

Federal regulations permit certain spouse-benefit trusts to receive disclaimed property, but the retained rights and powers must be carefully limited. An income interest or a principal invasion standard tied to health, education, support, or maintenance may be compatible with the plan. A power that allows the wife to appoint the property to herself, her estate, her creditors, or the creditors of her estate creates serious qualification and later estate-inclusion concerns.

---

7. What the QDOT Actually Solves

The QDOT addresses a different problem: the lack of an ordinary marital deduction for a noncitizen surviving spouse. A valid QDOT allows the estate to deduct qualifying property now while preserving a U.S. trustee and collection mechanism for estate tax that is deferred until later. It is a deferral structure, not a permanent exclusion.

In this $20 million case, the father's exclusion can shelter the first $15 million. Approximately $5 million remains above that exclusion. If the family wants that $5 million to benefit the wife and wants to avoid the approximately $2 million current tax shown earlier, the targeted federal solution is to place the excess share into a valid QDOT and make the QDOT election on Form 706.

A QDOT generally requires at least one trustee who is a U.S. citizen or a domestic corporation, restrictions that allow the U.S. trustee to withhold QDOT tax from principal distributions, compliance with regulatory collection and security requirements, and a timely executor election. Because the illustrative QDOT holds more than $2 million, the large-QDOT security rules—often involving a U.S. bank trustee, bond, or irrevocable letter of credit—must be addressed.

What happens after the QDOT is funded

• Income distributions to the wife are generally not QDOT-taxable distributions.
• Principal distributions generally trigger QDOT tax unless a statutory hardship exception applies.
• The property remaining in the QDOT at the wife's death generally triggers the deferred tax under IRC §2056A.
• The QDOT tax is computed by reference to the first decedent's federal estate-tax calculation; it is not simply erased by the wife's own exclusion amount.
• If the wife later becomes a U.S. citizen and satisfies the statutory conditions, future QDOT tax may cease to apply.

---

8. How the Disclaimer Trust and QDOT Work Together

The two trusts can coexist because they normally govern different shares of the same estate. The bypass trust is funded with property sheltered by the father's exclusion. The QDOT is funded with the excess property for which the estate needs a marital deduction.

The family therefore does not need to assume that the wife rejects the first $15 million. She may take it outright. She uses the disclaimer trust only if she prefers to receive economic support without having the legal ownership that would ordinarily place the assets and their growth into her later estate.

---

9. Four Federal Planning Outcomes Under the Same Facts

The alternatives below use the same $20 million estate and the same full $15 million exclusion. The difference is not the amount of the father's estate. The difference is who owns the property, whether a marital deduction is claimed, and when tax is imposed.

Plan A: $15 million outright plus a $5 million QDOT

This plan produces no current federal estate tax under the simplified assumptions. It is appropriate when the wife wants unrestricted ownership of the exclusion-funded share. The price of that control is potential inclusion of the outright property and its appreciation in her later estate.

Plan B: $15 million bypass trust plus a $5 million QDOT

This plan also produces no current federal estate tax. It is appropriate when the wife should receive support but the family wants the exclusion-funded assets and future growth to remain outside her later gross estate. It requires a timely, qualified disclaimer and continuing trust administration..

Plan C: no QDOT and payment of current tax

The family may choose simplicity and unrestricted ownership over deferral. If the full $20 million passes in a nondeductible manner and no other deductions apply, the estate pays approximately $2 million of current federal estate tax. The wife receives the after-tax property without QDOT administration.

---

10. What Happens When the Wife Later Dies

The father's $15 million exclusion is not “added back” at the wife's death. Instead, federal law asks what property the wife owns and what powers she holds when she dies. QDOT property follows a separate deferred-tax rule.

The statement that bypass-trust assets “are never taxed again” must be understood precisely. Properly structured bypass assets are generally not subjected to federal estate tax in the wife's estate. The trust can still earn taxable income, sell appreciated assets, incur capital gain, or create estate inclusion if the wife is later given prohibited ownership powers. The benefit is exclusion from her gross estate—not immunity from every federal tax.

---

11. The $194,000 Noncitizen-Spouse Amount Does Not Reduce the Estate at Death

For 2026, $194,000 is the special annual exclusion for qualifying lifetime gifts to a spouse who is not a U.S. citizen. It belongs to the gift-tax rules under IRC §2523(i). It is not a death-time marital deduction, it is not an additional estate-tax exemption, and it is not subtracted from the $5 million excess in this case study.

The simplified death-time calculation is therefore $20 million minus the father's $15 million exclusion, leaving $5 million of value that requires a deduction, another credit, or current tax. The estate does not reduce that $5 million to $4,806,000 by subtracting the $194,000 lifetime-gift amount.

---

12. Federal Filing and Administration Timeline

Because the gross estate exceeds the 2026 filing threshold, the Personal Representative must file Form 706 even if the final current estate tax is zero after applying the father's credit and a QDOT deduction. Several decisions occur within the same nine-month period, but they are not all governed by the same extension rules.

---

13. How the Federal Plan Is Positioned More Effectively

A defensible plan follows the economic objective rather than placing assets into trusts by reflex:

1. Confirm the father's remaining exclusion. Prior taxable gifts can reduce the amount available at death.

2. Identify the wife's ownership objective. If she wants full ownership of the exclusion-funded share, no disclaimer or QDOT is required for that share.

3. Use the disclaimer trust only when the estate document already provides the correct fallback trust and the family wants support without ownership.

4. Limit the QDOT to the share that needs a marital deduction.

5. Coordinate probate and nonprobate property. Joint accounts, life insurance, retirement benefits, and payable-on-death assets may not follow the will and can frustrate the intended funding formula.

6. Model second-death estate tax and basis together. Keeping property outside the wife's estate may save estate tax but may also forgo a second basis adjustment.

7. Address citizenship and treaty possibilities before finalizing the return. Either can materially change the default QDOT analysis.

8. Document ongoing QDOT compliance. The first-death election begins, rather than ends, the deferred-tax administration.

---

Conclusion: The Exclusion Comes First; the QDOT Is a Targeted Deferral Tool

This case does not begin with the assumption that the wife refuses or does not want the father's $15 million exclusion-funded share. She may receive that share outright and the father's available credit can eliminate current federal estate tax on it. No QDOT is required for that result.

The disclaimer trust answers a different question: should the wife own the exclusion-funded property, or should she receive support from it while the assets remain outside her later gross estate? If she wants ownership, she should not disclaim merely for form's sake. If the family wants benefit without ownership, the existing disclaimer provision may route the property to a properly structured bypass trust.

The QDOT addresses the remaining federal problem. Approximately $5 million exceeds the father's available $15 million exclusion. If that excess is intended for the noncitizen wife and the estate wants to defer approximately $2 million of current tax, the QDOT marital deduction is the principal federal mechanism. The disclaimer trust and QDOT can therefore operate together, but they apply to different shares and solve different problems.

Selected Federal Authorities and Source Notes

Professional-Use Disclaimer

This article is educational and simplifies complex federal transfer-tax rules. Actual results depend on the governing instruments, beneficiary designations, prior taxable gifts, valuation, deductions, citizenship, treaty provisions, trust powers, asset acceptance, and timing. A qualified disclaimer is irrevocable and time-sensitive. Coordinated legal and tax advice is required before accepting assets, executing a disclaimer, funding a bypass trust or QDOT, or making Form 706 elections.