US citizenship: the permanent worldwide estate tax connector
The US is the only major country that uses citizenship — not domicile, not residence — as the basis for worldwide estate tax. No planning, no treaty, and no move abroad eliminates this obligation.
US citizenship: the permanent worldwide estate tax connector
The US is the only major country that uses citizenship — not domicile, not residence — as the basis for worldwide estate tax. No planning, no treaty, and no move abroad eliminates this obligation.
Approximately 5.5 million US citizens live outside the United States. Most of them owe US estate tax on their worldwide assets above the applicable exemption — regardless of where they live, where their assets are, where their heirs live, or how long they have been abroad. This is not a feature of most countries’ tax systems. It is unique to the United States, and it is permanent.
Principle 01 — The citizenship connector
US federal estate tax applies to the worldwide estate of any US citizen, in any country, at death. The applicable law is the Internal Revenue Code (IRC §2001 et seq.). There is no length-of-residence threshold, no domicile requirement, and no exemption based on years spent abroad.
The $15m exemption sounds generous — but it applies to the worldwide estate. A US citizen living in London with a UK home, investment portfolio, and US retirement accounts can easily approach or exceed $15m in combined worldwide assets, particularly when retirement accounts and life insurance are included.
Principle 02 — What no treaty can fix
Every US bilateral estate tax treaty contains an explicit citizenship carve-out. The US/UK 1978 treaty, the US/France 1978 convention, the US/Germany 1982 treaty, and all others preserve the US right to tax its citizens on worldwide assets regardless of the treaty’s domicile tie-break. This means:
- A US citizen living in London for 30 years, with a UK-domicile argument, is not protected by the US/UK treaty from US worldwide estate tax
- A US citizen married to a French national, living in Paris, faces US estate tax on worldwide assets even though the US/France convention provides domicile relief for non-citizens
- No treaty, in any country, removes worldwide US estate tax exposure for US citizens
Principle 03 — The non-citizen spouse problem
The US unlimited marital deduction — which allows spouses to inherit free of estate tax — is only available to US citizen spouses. A US citizen who leaves their estate to a spouse who is not a US citizen loses the marital deduction entirely. The federal estate tax on amounts above the $15m exemption becomes immediately payable at death.
The solution is a Qualified Domestic Trust (QDOT), which defers (not eliminates) estate tax until the non-citizen spouse’s death, provided the assets remain in the QDOT. This is a specialist structure that requires careful drafting and ongoing compliance. It is missed in a significant proportion of US expat estates.
Principle 04 — State estate taxes
Twelve US states impose their own estate taxes with significantly lower exemption thresholds than the federal $15m. The most significant: Massachusetts ($2m exemption, up to 16% rate), Oregon ($1m exemption, up to 16%), Washington State ($2.193m, up to 20%), New York ($7.16m, up to 16%), Illinois ($4m, up to 16%). A US citizen living in London with a Massachusetts vacation home could face Massachusetts estate tax on that property regardless of their UK domicile.
Principle 05 — Renunciation of US citizenship
The US imposes an “exit tax” on renunciation for individuals who meet the covered expatriate threshold (net worth above $2m, average annual net tax liability above ~$200k, or failure to certify 5 years of tax compliance). The exit tax is a deemed disposal of all worldwide assets at fair market value on the day before expatriation date. It does not eliminate the estate tax obligation on future inheritance if the renunciant has covered expatriate status.
The most important first step for any US citizen abroad is to quantify the worldwide estate. Include all assets in all countries: UK pension (if any), ISAs, UK property, US retirement accounts (IRAs, 401k), life insurance with estate as beneficiary, and any business interests. Then assess whether the $15m threshold is relevant, what state exposures exist, and whether the QDOT issue applies.
Planning triggers — you should be reviewing this if…
- You are a US citizen living outside the US — any estate above $15m is exposed
- Your spouse is not a US citizen — the QDOT issue applies to your estate plan
- You own property or assets in a US state with a state estate tax
- You have a US retirement account (IRA, 401k, Roth) and have not assessed how it interacts with the estate of your non-US-resident heirs
- You are considering renouncing US citizenship — the exit tax implications require specialist advice first
- You have a trust structure that was designed without considering the US estate tax treatment of the trust interests
What this article cannot tell you
- Whether any bilateral tax treaty provides relief for your specific corridor — requires specialist US and foreign tax analysis
- Whether your worldwide estate approaches the $15m threshold and by how much — requires full asset mapping
- Whether QDOT is appropriate for your family structure — requires specialist US estate planning advice
- The state estate tax position for your specific US state(s) of connection
- Whether renunciation is appropriate or advantageous for your situation
Frequently Asked Questions
Do I owe US estate tax if I live abroad?
Yes, if you are a US citizen. The US taxes worldwide estates of all US citizens above the applicable exemption ($15m from January 2026) regardless of where you live, where your assets are, or where your heirs live. No bilateral estate tax treaty removes this. Moving abroad, changing domicile, or spending decades outside the US does not eliminate the obligation.
What is the US estate tax exemption in 2026?
The federal unified estate and gift tax exemption is $15 million per individual from January 1 2026, made permanent by the One Big Beautiful Bill Act (signed 2025). For married couples, portability allows the surviving spouse to use the deceased spouse’s unused exemption, potentially sheltering $30m combined. State estate taxes apply separately — Massachusetts has a $2m threshold, Oregon $1m, Washington State $2.193m.
Does a US estate tax treaty protect US citizens living abroad?
No. Every US bilateral estate tax treaty contains a citizenship carve-out that preserves the US right to tax its citizens on worldwide estates regardless of where they are domiciled. Treaties help non-citizen US domiciliaries — not US citizens. A US citizen in the UK, France, Germany, or Australia is not protected from worldwide US estate tax by the applicable treaty.
My spouse is not a US citizen — what happens on my death?
The US unlimited marital deduction — which eliminates estate tax on assets passing to a surviving spouse — only applies to US citizen spouses. If your spouse is not a US citizen, the marital deduction is unavailable and US estate tax above the $15m exemption is immediately payable at your death. The solution is a Qualified Domestic Trust (QDOT), which defers (not eliminates) the tax until the non-citizen spouse’s death, provided assets remain in the QDOT. This requires specialist US estate planning advice.
Can I avoid US estate tax by renouncing citizenship?
Renunciation does not automatically eliminate US estate tax obligations. For covered expatriates (net worth above $2m or meeting other thresholds), renunciation triggers an exit tax — a deemed disposal of all worldwide assets at fair market value. Additionally, the US imposes a 40% inheritance tax on US citizens who receive gifts or bequests from covered expatriates above a threshold. Renunciation requires careful specialist analysis before proceeding.
Are IRAs and 401(k) accounts included in the US estate for estate tax purposes?
Generally yes. US retirement accounts (IRAs, 401(k)s, Roth IRAs) are included in the gross US estate at their full account balance as of the date of death. For US citizens abroad with non-US-resident beneficiaries, the interaction between the US estate tax inclusion and the beneficiary’s country’s inheritance tax rules creates additional complexity. Some bilateral tax treaties address this partially, but country-specific analysis is required.
FAQs are for general educational purposes only. Not legal, tax or financial advice.
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