Cross‑border marriages are becoming increasingly common, and so are the estate planning surprises that come with them. If at least one spouse is not a U.S. citizen, familiar tools like the unlimited marital deduction and portability may not work as expected. With thoughtful planning, you can retain flexibility while also managing tax exposure and protecting family wealth.
For purposes of this post, a “Citizen” is a U.S. citizen; a “Resident” means a U.S. resident; and a “Non‑Citizen” includes Residents and people who are neither U.S. citizens nor U.S. residents.
Key Differences in Planning Rules for Mixed-Citizenship Couples
- No Unlimited Marital Deduction if Receiving Spouse is Not a Citizen
Generally, Citizens and Residents can transfer wealth during life or at death up to the federal estate and gift tax exemption (the “Exemption Amount”) without owing estate or gift tax. Transfers made during life or at death in excess of the Exemption Amount are generally taxable.
When both spouses are Citizens, a special rule applies: each spouse can transfer an unlimited amount to the other free of estate and gift tax. This “Unlimited Marital Deduction” allows a Citizen to (a) make unlimited lifetime gifts to a Citizen spouse without using any Exemption Amount and (b) pass an entire estate to a Citizen spouse at death without estate tax.
However, the Unlimited Marital Deduction does not apply if the receiving spouse is not a Citizen. To help offset this limitation, there is a higher annual exclusion for gifts to a Non‑Citizen spouse. Generally, a person can give up to the standard annual exclusion to anyone each year without gift tax. For gifts to a Non‑Citizen spouse, the limit is higher. For example, in 2026, the standard annual exclusion is $19,000, but a Citizen can give up to $194,000 to a Non‑Citizen spouse tax‑free.
- Portability Not Available if Either Spouse is Not a Citizen or Resident
When both spouses are Citizens or Residents, the federal estate tax rules allow any unused portion of a deceased spouse’s Exemption Amount (DSUE) to be transferred to the surviving spouse. By adding the DSUE amount to his or her own Exemption Amount, the surviving spouse can increase the total amount they may transfer tax-free during life or at death. The ability to transfer the DSUE amount from one spouse to another is referred to as “portability.”
Portability only applies if both spouses are either a Citizen or Resident (unless a treaty says otherwise). However, even if the surviving spouse is a Resident and portability is otherwise allowed, there may be limits on how the DSUE amount can be used. For example, if property passes to a Qualified Domestic Trust (QDOT) for the benefit of a Resident surviving spouse, the DSUE generally becomes available only when the QDOT terminates. Practically speaking, this prevents the surviving spouse from using the DSUE amount for lifetime gifts while the QDOT is in place.
Different Reporting Rules
Mixed-citizenship couples often hold financial assets or bank accounts in multiple countries. When the value of these foreign assets exceeds certain thresholds, U.S. taxpayers may face additional IRS reporting requirements. Failure to file may result in severe penalties.
For example, foreign bank and financial accounts may require the filing of an annual FBAR if the aggregate value of all foreign accounts (including joint accounts) exceeds $10,000 at any point in the year. Moreover, certain foreign financial assets may need to be reported on Form 8938 with an income tax return once thresholds are met, including foreign trusts and pensions. U.S. taxpayers who receive more than $100,000 in gifts or bequests from a foreign person, including a Non‑Citizen spouse, generally must file Form 3520. These filings are separate from any tax owed, and penalties can apply even when no tax is due. It is important to coordinate among spouses, advisors and family office teams to help avoid mistakes.
Estate Planning Moves That Work
- Qualified Domestic Trusts. As mentioned above, if one spouse is not a Citizen, the general rule is that they cannot take advantage of the Unlimited Marital Deduction. The QDOT is one important exception. Assets passing to a properly structured QDOT can qualify for the Unlimited Marital Deduction, deferring estate tax until principal is distributed (subject to a hardship exception) or until the trust terminates. Note that the trust must meet specific rules to qualify as a QDOT. For example, the trust must prohibit distributions of principal unless a U.S. trustee has the right to withhold tax on such distributions.
- Treaties. The United States has established estate and/or gift tax treaties with several countries, which are designed primarily to prevent or minimize double taxation of lifetime transfers and transfers at death. Some treaties even provide marital deduction benefits to Non-Citizen spouses. Treaties can be helpful tools depending on the citizenship of the Non-Citizen spouse.
- Naturalization. Of course, pursuing U.S. citizenship can unlock even more options. For example, if a surviving spouse becomes a Citizen before the deceased spouse’s estate tax return is due, and has been a U.S. resident continuously since death, the survivor may qualify retroactively for the Unlimited Marital Deduction.
Practical Takeaways
Mixed‑citizenship marriages call for tailored planning, not a standard spousal plan. We recommend:
- Using the enhanced annual exclusion to rebalance assets over time.
- Evaluating whether a QDOT, treaty relief or a mix of both fits your goals.
- Monitoring the value of foreign bank accounts, and marking your calendar for FBAR, Form 8938 and Form 3520 filings.
- Revisiting the estate plan and strategy at major life events (such as naturalization).
