Take a man we will call Thomas. He is a composite of several families, so there is no point looking for him. But every element of his situation is one that comes up in practice.
Thomas was British, in his sixties, and he had done everything right. A house in Spain, where he and his wife had lived for eleven years. A brokerage account in the United States, full of the American shares everyone recommends. An old bank account and a small flat in England, kept from his working years. A will, even, drawn up by his solicitor in 2004, long before he left.
Then Thomas died. And his widow found that nobody, anywhere, was in charge.
The Spanish bank froze the accounts the moment it learned of the death. The American broker asked for paperwork from the IRS she had never heard of. The English bank wanted probate before it would release the account. Three countries, three legal systems, three tax administrations, and one grieving woman in the middle with a stack of folders.
This is the quiet mess of cross-border inheritance. It sits where two systems meet that do not work together: the law that decides who inherits, and the taxes that decide what the heirs keep. Most people who live abroad have settled neither.
The rule that decides who inherits
Inside the EU there is at least one rule. The EU Succession Regulation (EU) No 650/2012 applies to the estates of people who die on or after 17 August 2015. Its Article 21 says that the law applicable to the succession as a whole is the law of the state in which the deceased had his habitual residence at the time of death.
Read that again if you are British and live in Valencia, or Irish and live in Lisbon. Your estate, all of it, worldwide, is by default governed by Spanish or Portuguese succession law. Not the law of your passport. The law of the place you live. Article 20 makes clear that the law the Regulation points to applies even where it is not the law of an EU member state.
For Thomas, that meant Spanish law decided who inherited: the house in Spain, the flat in England and, in principle, the American shares. His 2004 will was not void. It was simply written for a legal world he had left.
The Regulation also contains the most valuable sentence in this whole field. Article 22: a person may choose, as the law to govern his succession as a whole, the law of the state whose nationality he possesses. The choice must be made expressly in a declaration in the form of a disposition of property upon death, or follow clearly from its terms. In plain language: it goes into your will. One paragraph. That paragraph decides whether your family deals with a legal system it understands or one it does not.
Two caveats. First, the Regulation does not bind the United Kingdom, Ireland or Denmark. Its own recitals say so: none of the three took part in its adoption. A Briton in Marbella or a Dane with a flat in Berlin is dealing with systems that do not share a rulebook, and how they interact is not always clear even to specialists. Second, the Regulation solves only half the problem.
The law is not the tax
Article 1 of the Regulation says it in one line: it does not apply to revenue matters. The EU harmonised whose law governs the inheritance. It did nothing about who taxes it. Inheritance tax stays national. Every country where you hold assets, or where you or your heirs live, applies its own rules to the same estate at the same time.
The United Kingdom moved to a residence test on 6 April 2025. You are a long-term UK resident if you were UK tax-resident for at least 10 of the previous 20 tax years, and a long-term resident is charged on overseas assets as well, at 40% above the £325,000 threshold. The status does not end on the day you leave. According to HMRC's guidance it continues for up to 10 tax years after departure: three years if you lived in the UK for 10 to 13 years, four years after 14 years, five after 15, and so on. Someone who left London for Dubai four years ago, after twenty years in the UK, can die a Dubai resident and still be inside the UK net with his worldwide estate. Someone who is not a long-term resident pays inheritance tax only on UK assets, such as a flat or a bank account in the UK. Thomas's English flat was one of those.
The United States reaches non-Americans through their American assets. Shares in US companies count as US property no matter where the certificates are held, according to the IRS instructions for Form 706-NA. Where the US assets of a deceased non-resident, together with certain lifetime gifts, exceed $60,000, the executor must file Form 706-NA, normally within nine months of death. The top rate on the estate tax schedule is 40%. Before US assets can be released, a transfer certificate from the IRS is generally needed, and where no Form 706-NA was required, the IRS itself states a processing time of 12 to 18 months for the affidavit and documents once it has all of them.
Spain taxes heirs who are habitually resident in Spain on everything they receive, wherever the assets are, under Article 6 of its Inheritance and Gift Tax Act.
So picture Thomas's estate again. Spanish law decides who inherits. Spain taxes his Spanish-resident heirs. The UK taxes the English flat. The United States reaches the brokerage account before anyone can touch it. Several tax claims, partly overlapping, each with its own deadlines and forms. The law question and the tax question are answered in different buildings, in different languages, on different clocks.
What the banks do
Then there is the practical layer, which no statute describes.
When a bank learns of a death, the account is frozen. That is self-protection, not malice: the bank does not know who the heirs are and will not guess. What releases the account is proof of inheritance in a form that bank's legal department accepts, and each country has its own. In England it is probate. Elsewhere it is a notarial deed or a court certificate.
The EU created a European Certificate of Succession to bridge exactly this gap. Under Article 62 of the Regulation it is issued for use in another member state, its use is optional, and it does not replace the national documents. A bank in London or New York is not bound by it.
Every document from one country usually needs legalising, typically by apostille, and a sworn translation before another country accepts it. Each step takes time, and the steps run one after another. For an estate in three countries, frozen accounts are measured in months, not weeks. Meanwhile the mortgage still has to be paid, and the money sits on a screen the widow can see and cannot use. Access after death has to be arranged before death. Afterwards it is too late.
Forced heirship
One more trap, and it mainly catches the British and the Irish, who grew up with the idea that you may leave your money to whomever you like.
Spain reserves a share of the estate for the children that no will can take away. Under Articles 806 to 808 of the Spanish Civil Code, two thirds of the estate are reserved for the children and descendants; the parent may use one of those two thirds to favour one child over the others, and only the remaining third is free. A British testator who lives in Spain and has made no choice of law finds this out too late, through his lawyer, via children who are either furious or delighted.
The choice of law under Article 22 is the instrument for this. If your plan quietly assumes English testamentary freedom while Spanish law governs, the plan and the law are not on speaking terms.
What to settle now
None of this is exotic. All of it is tedious, which is exactly why it does not get done.
One: make a choice of law, or make one will per legal system, but decide deliberately. For a national of an EU state living in the EU, a choice of the law of nationality under Article 22 in one carefully drafted will is often the cleanest route. Where assets sit in systems the Regulation does not bind, such as the UK or the US, separate wills per jurisdiction, drafted so that they do not revoke each other, are often better. What harms families is the third option: the old will that decided nothing.
Two: use beneficiary designations where the system offers them. US brokerage accounts can carry a transfer-on-death registration; according to FINRA, ownership then passes to the named beneficiaries and the assets generally avoid probate, although estate tax may still apply. Every asset that passes by designation is one asset fewer in the frozen pile.
Three: liquidity outside the estate. Powers of attorney do not solve this everywhere. In England a lasting power of attorney usually ends when the donor dies. Whatever your countries allow, the aim is the same: your spouse must be able to pay the bills in month two, not month fourteen.
Four: write the map. An inventory of every account, every property, every policy and every structure, where the documents are and who the contacts are. On paper, updated every year, its location known to the family. Estates lose money not only to tax but to assets nobody knew existed.
For families with substantial wealth in several countries, holding assets through the right structure can also reduce the number of estates that have to be settled. Our estate planning page shows how we approach succession, and inheritance tax sets out the UK position in more detail. If a move abroad is part of the plan, the rules on leaving the UK belong in the same conversation.
Thomas's widow got there in the end. Nearly two years, five-figure professional fees, and a year of her life she will not get back, for an estate that was never in dispute for a single day. Almost all of it could have been avoided by a few afternoons of unglamorous work while Thomas was alive.
You have one estate. The mess is optional.