Accumulating assets across multiple countries is a natural consequence of an internationally mobile life. A flat in London, a villa in Spain, a brokerage account in Singapore, and a share portfolio in the UAE is not an unusual picture for a globally oriented family. What is unusual — and often dangerously overlooked — is that each of those assets sits within a different legal system, and each of those legal systems has its own views on who inherits it.
Cross-border estate planning is the discipline of imposing order on that complexity before it becomes someone else's problem. Leaving it unaddressed does not mean your estate will pass as you intended. It often means years of competing legal proceedings, family disagreements adjudicated in courts you have never set foot in, and a substantial portion of your estate consumed by legal fees.
The Foundation: Understanding UK Domicile
For British nationals, the starting point is almost always domicile — a concept that is frequently confused with tax residence but is entirely different.
Domicile of origin is acquired at birth and is typically the domicile of your father. It is remarkably sticky: you carry it until you actively abandon it, and it can revive if you lose an acquired domicile without replacing it.
Domicile of choice is acquired by settling in a country with the intention to remain there permanently or indefinitely. The courts apply a high evidential bar: HMRC and the courts have consistently held that international professionals who move abroad for work, maintain a UK home, keep children in UK schools, and hold a British passport are rarely domiciled anywhere other than the UK regardless of how many years they have spent overseas.
Why does this matter? Because the UK imposes inheritance tax on the worldwide estate of a UK-domiciled individual, regardless of where those assets are held. A UK domiciliary who dies owning property in Thailand, stocks in the UAE, and a pension in the UK faces UK IHT on all of it — at 40% above the nil-rate band (currently £325,000, or £500,000 where the residence nil-rate band is available and a main home passes to direct descendants).
The non-domicile rules that long allowed long-term UK residents to shield non-UK assets from IHT have been substantially curtailed. Since April 2025, individuals who have been UK resident for at least 10 of the last 20 tax years are treated as "long-term residents" for IHT purposes, bringing their non-UK assets within the UK charge. This change affects many internationally mobile families who previously assumed their overseas assets were protected.
Forced Heirship: The Invisible Constraint
Freedom of testation — the ability to leave your estate to whomever you choose — is not a universal legal principle. Many civil-law countries impose forced heirship rules that reserve a portion of the estate (the réserve or legitim) for close relatives regardless of what a will says.
France reserves between half and three-quarters of the estate for children, depending on the number of children. EU Succession Regulation (Brussels IV) allows individuals to elect the law of their nationality — meaning a British national owning French property can elect English law to govern the succession of that property. This election mechanism remains available to UK nationals post-Brexit (Brussels IV applies to assets sited in EU member states regardless of the testator's nationality). However, a 2021 amendment to Article 913 of the French Civil Code introduced a compensation mechanism (droit de prélèvement) that allows disinherited children with EU nationality or habitual residence to claim what they would have received under French forced heirship rules, even where an English law election has been made — substantially reducing the practical effectiveness of a Brussels IV election in many cases. The position requires specialist French legal advice.
Spain similarly reserves two-thirds of the estate for children in various proportions. The legitimate heir's portion cannot be diminished by will. Property in Spain is governed by Spanish succession law for Spanish-sited assets unless the EU Succession Regulation applies.
UAE applies Sharia succession law to Muslim nationals, but non-Muslims can register wills with the DIFC Wills Service or the Abu Dhabi Judicial Department covering UAE-based assets. Without a registered will, a non-Muslim foreigner's UAE estate will default to Sharia principles, which may produce a distribution entirely at odds with their intentions.
Thailand does not allow foreigners to own land outright. Condominiums can be owned freehold, and succession follows Thai law for Thai-sited assets. A will registered in Thailand is strongly advisable for any Thailand-based property.
The United States, despite being a common-law country, has state-level forced heirship rules in some jurisdictions (Louisiana being the notable example) and complex federal estate tax rules for non-citizens.
The critical point is that forced heirship rules apply to assets sited in the relevant country regardless of what your home-country will says. Your English will may validly distribute your English assets — but it has no authority over what Spanish law mandates for your Spanish apartment.
The Mirror Wills Problem
A common approach for couples is to execute mirror wills — each leaving their estate to the other, and then to their children. This is straightforward in a single jurisdiction, but in multi-jurisdiction estates it creates several problems.
The revocation trap: In many jurisdictions, marriage revokes an earlier will. In England and Wales, a will is revoked by marriage unless it was made in contemplation of that marriage. If you execute an English will, then marry abroad, and the marriage is recognised in England, your English will may be revoked entirely.
The simultaneous death problem: Mirror wills typically include a survivorship clause (the beneficiary must survive the testator by, say, 28 days to inherit). Where assets span multiple jurisdictions, determining the order of death and applying survivorship clauses consistently across four or five legal systems is complex.
The foreign-law surprise: A mirror will that works perfectly under English law may produce unintended consequences when a foreign jurisdiction applies its own forced heirship rules to the same assets. A Spanish spouse's inheritance from a British testator may face Spanish IHT rules rather than UK ones for the Spanish property.
The practical solution: Rather than mirror wills, internationally mobile families typically benefit from a suite of jurisdiction-specific wills — one for each country where they hold significant assets — coordinated so that they do not inadvertently revoke each other. Each will should contain an express statement that it relates only to assets in that jurisdiction and does not revoke any other will.
This requires coordination between solicitors in multiple countries. The cost is not trivial. But it is a fraction of what contested multi-jurisdiction probate proceedings cost.
International Trustees: When a Trust Crosses Borders
Trusts can be powerful estate planning vehicles, but their cross-border operation requires careful management.
A trust established under English law, with a UK-resident settlor, may hold assets in several countries. If trustees are resident in multiple countries, the trust may be treated as resident in all of those countries simultaneously — creating potential multiple taxation of trust income.
For trusts holding US-sited assets or with US-person beneficiaries, US tax rules (including FBAR reporting and PFIC rules) layer additional complexity over the English law structure.
The choice of trustees — and their residence — is therefore not merely an administrative decision. A professional trustee resident in a low-tax jurisdiction with an established trust law framework (Jersey, Guernsey, Cayman, BVI) provides certainty of residence for the trust and access to infrastructure developed specifically for managing international trust structures.
Trustee succession is also critical in cross-border trusts. A trust whose sole trustee dies or loses capacity can be frozen while the courts of the relevant jurisdiction appoint a replacement. Successor trustee provisions and the use of a trust protector (an independent party with power to remove and replace trustees) are standard practice in professionally drafted international trust structures.
Powers of Attorney Across Borders
If you lose mental capacity while living in or visiting a foreign country, who can act on your behalf for your UK assets? The answer depends on whether you have registered a Lasting Power of Attorney (LPA) in England and Wales.
An English LPA, registered with the Office of the Public Guardian, is valid for UK-based assets. It does not automatically extend to assets held in other countries, which may have their own requirements for foreign power of attorney instruments (notarisation, apostille, translation, or local re-registration).
For internationally mobile individuals, the practical minimum is:
- A registered English LPA for UK assets
- A local equivalent in any country where significant assets are held
- Clarity among family members about who holds which document and where it is registered
Practical Steps: The Multi-Jurisdiction Estate Plan
Prepare a complete asset inventory — by country and asset class. This is the foundation for everything else and is frequently the step that families skip.
Identify which law governs each asset — generally, moveable property (investments, cash) is governed by your domicile; immoveable property (real estate) is governed by the lex situs (the law of the country where it sits).
Commission a coordinated will suite — one will per jurisdiction, drafted so they do not revoke each other, with each covering only the assets in that country.
Review your trust structures — if you have existing trusts, check trustee residence, trust residence for tax purposes, and compliance with the local rules of each country where trust assets are held.
Register LPAs and equivalent documents — do not assume your English LPA is sufficient for overseas assets.
Plan for UK IHT — if you are or may be UK-domiciled, model the IHT exposure on your worldwide estate and consider whether trusts, life insurance (written in trust), or other IHT mitigation strategies are appropriate.
Review every five years — or after any major life event (marriage, divorce, the death of a beneficiary or trustee, moving country, acquiring a major new asset).
Compliance Caveat
Tax laws, succession rules, and domicile determinations are complex and change regularly. The information in this article is for general educational purposes. The applicable rules in your specific circumstances depend on your domicile, residence, nationality, and the nature of the assets involved. Rules described here are as understood as of mid-2026 and may have changed. You should obtain specific legal and tax advice from qualified professionals in each relevant jurisdiction before making any estate planning decisions.
How Global Investments Can Help
Global Investments works with internationally mobile high-net-worth families navigating precisely this kind of complexity. We coordinate with specialist solicitors, tax advisers, and trust companies across the jurisdictions where our clients hold assets — ensuring that your estate plan is coherent across borders, not just technically valid in one country and silently overridden by the laws of another.
Whether you need a comprehensive audit of your existing arrangements, help commissioning a coordinated will suite, or guidance on whether a trust structure makes sense for your specific situation, our advisers can help you build an estate plan that works as you intend it to — wherever your assets are held and wherever in the world your family is living. Contact us to arrange an initial consultation.
This article is for general information only and does not constitute financial, legal or tax advice. Rules, prices and regulations change; verify current requirements with a qualified adviser before acting.