A Cross-Border Will for US and UK Couples: One Will or Two?

A cross-border will for a US/UK couple can be one will covering everything or two coordinated wills, one for each country. Both can work. One will is simpler to keep up to date; two wills usually make probate faster where there is property or large accounts in both countries. What matters more than the number is that the drafting fits both legal systems and the spouse tax rules on each side.

Couples where one partner is American and the other British, or where both are Americans living in England, ask us this question more than almost any other about estate planning. The honest answer is that the number of wills is a practical choice. The risks sit elsewhere: a revocation clause that cancels the other will, a marriage that silently cancels an old will, and spouse tax rules that treat a foreign husband or wife less generously than a local one. This guide works through each in turn, then sets out a step-by-step plan.

Does a cross-border couple need one will or two?

A cross-border couple needs at least one valid will that deals with every asset, and many are better served by two. The deciding factors are where the assets are, how each country's probate process handles a foreign document, and who will act as executor in each place.

A single will is often enough where nearly everything sits in one country, for example a London home, UK pensions and UK bank accounts, with only a modest US brokerage account. Two wills tend to make sense where there is real estate in both countries, or significant accounts held by US institutions that will want to see a local court order before they release funds.

Question	One will	Two coordinated wills
Cost to set up	Lower: one document, one adviser	Higher: drafting in both countries, coordinated
Keeping it up to date	One document to review	Both must be reviewed together after any change
Probate in the other country	May need extra evidence of foreign law and a certified copy	Each will goes through its own local process
Risk of one will cancelling the other	None	Real, unless revocation clauses are limited carefully
Executors	The same people act everywhere	A local executor can be named for each country
Best suited to	Estates mostly in one country	Property or large accounts in both countries

Neither column changes the tax. Inheritance Tax and US estate tax are charged on the estate according to residence, citizenship and where assets sit, not on the number of documents. Our guide to US/UK mixed couple tax planning covers the lifetime side of the same decisions.

Is a US will valid in the UK, and a UK will valid in the US?

A will signed in the US is usually formally valid in England and Wales, and an English will is usually accepted in the US. The question for executors is less "is it valid?" and more "how much work will it take to prove it?"

How England and Wales treat a foreign will

Section 1 of the Wills Act 1963 treats a will as properly executed if its signing followed the internal law of the territory where it was made, or of the place where the testator was domiciled or habitually resident, or of a state of which they were a national, either when the will was signed or at death. A will signed in New York by a New Yorker who later moved to London will usually pass that test.

An English will, for comparison, needs the formalities on GOV.UK's page on making a legal will: the person making it must be 18 or over and sign it in the presence of two witnesses who are both over 18, who then sign it in their presence. A witness, or a witness's spouse or civil partner, cannot benefit under the will. That last rule catches couples who ask each other to witness.

How US states treat an English will

There is no federal law of wills in the United States. Each state sets its own rules for signing, witnessing and probate, and many states accept a will that was validly signed where it was made. Even so, a US court may ask for more than it would for a local will, such as proof that the witnesses signed properly, which can be harder to produce years later from another country. That practical friction is the main argument for a separate US will where there is US real estate.

Scotland and Northern Ireland have their own will and succession rules, which GOV.UK points to from its making a will guide. This article describes the position in England and Wales.

The revocation trap in a two-document cross-border will plan

The biggest risk in a two-will cross-border will plan is that the second will cancels the first. Most standard wills open by revoking "all previous wills and codicils". GOV.UK's guidance on updating a will says exactly that: a new will should explain that it revokes all previous wills and codicils. For someone with one will, that is the right advice. For someone with a US will and a UK will, it can wipe out the other document.

The fix is drafting, not luck. Each will should:

• say which assets it covers, for example "my property situated in the United Kingdom" and "my property situated in the United States";
• revoke only earlier wills that dealt with the same assets, and say expressly that it does not revoke the other country's will;
• refer to the other will by date, so an executor can see the two were written as a pair;
• avoid leaving the same asset or the same residue twice, and avoid leaving any asset out of both.

The same care applies every time one will is updated. Changing the UK will after a house move, without looking at the US will, is how gaps and overlaps appear.

Marriage, divorce and an old will

Life events change English wills in ways American clients often do not expect. GOV.UK says plainly that getting married cancels any will you made before. A couple who wrote wills in the US, moved to London and then married here may find that English law treats those wills as revoked, unless the will was made in contemplation of that marriage.

Divorce works differently. It does not cancel the whole will. Under section 18A of the Wills Act 1837, gifts to a former spouse and their appointment as executor take effect as if the former spouse had died on the date the marriage was dissolved or annulled, unless the will shows a different intention. Each US state has its own rules on how marriage and divorce affect a will, so both documents need a review after either event. Our guide to tax for a surviving spouse in the US and UK picks up what happens after a death.

How do spouse tax rules shape a cross-border will?

Spouse tax rules shape a cross-border will because both countries give less relief when the surviving spouse is foreign. A will that leaves everything to the other spouse can be tax-free between two local spouses and expensive between an American and a Briton.

On the US side: the non-citizen spouse

The US normally lets a person leave any amount to a spouse free of estate tax through the marital deduction. That deduction is generally not available where the surviving spouse is not a US citizen unless the assets pass to a qualified domestic trust (QDOT). The IRS instructions for Form 706-QDT explain how distributions from those trusts are taxed later.

Whether this matters depends on size. The IRS says on its estate and gift tax update page that the basic exclusion amount is $15,000,000 for 2026. During life, Revenue Procedure 2025-32 sets the 2026 annual exclusion at $19,000 per recipient, and at $194,000 for gifts to a spouse who is not a US citizen. Gifts above those amounts need a US gift tax return; our gift tax return service handles them.

A British spouse who is not American and who holds US shares or US property faces a separate issue: the IRS says a Form 706-NA estate return is needed where a non-resident non-citizen's US-situated assets exceed $60,000. We explain that threshold in US estate tax for a non-resident in the UK.

On the UK side: the spouse exemption limit

Inheritance Tax is usually not charged on what one spouse leaves the other. HMRC restricts that exemption where the spouse making the transfer is a long-term UK resident and the recipient is not. HMRC's manual at IHTM47030 limits the exemption to the nil-rate band at the date of transfer, counted across all transfers to that spouse. The nil-rate band is £325,000 and the residence nil-rate band £175,000 for 2026 to 2027, both fixed until the end of 2030 to 2031.

The non-resident spouse can elect to be treated as a long-term UK resident, which removes the cap. HMRC's manual at IHTM47031 says the election cannot be revoked and lapses only after 10 consecutive years of non-UK residence, and it brings the electing spouse's worldwide assets into Inheritance Tax. The US/UK estate and gift tax treaty offers another route for some American estates. We cover it in the US UK estate tax treaty and the long-term residence test in UK Inheritance Tax for Americans.

Illustrative example, with invented figures: Daniel is a US citizen who has lived in England for more than ten years and is a long-term UK resident. His wife, Sophie, is French, lived in the US until recently and is not a long-term UK resident. Daniel's single English will leaves everything to Sophie: a London flat worth £900,000 and a US investment account. On the UK side, the spouse exemption is capped at £325,000 because Sophie is not a long-term UK resident, so the rest could fall into Inheritance Tax unless Sophie elects or another relief applies. On the US side, Sophie is not a US citizen, so a gift to her outright would not qualify for the marital deduction, but Daniel's estate is far below the $15,000,000 basic exclusion for 2026 and owes no US estate tax. The fix here is on the UK side, and the choice between an election and other planning is one to model before anyone dies.

What happens if a US/UK couple has no will?

Without a will, each country's intestacy rules decide who inherits the assets under its control, and the results do not have to match. In England and Wales, where someone dies leaving a spouse or civil partner and children, the spouse takes the personal possessions, a fixed sum and half of what remains; the children share the other half. The Fixed Net Sum Order 2023 set that fixed sum at £322,000 from 26 July 2023.

English intestacy gives nothing to an unmarried partner, however long the relationship. US states each have their own intestacy rules, and the spouse's share differs from state to state. An intestate estate can also leave the surviving spouse without the trust structures, such as a QDOT, that would have reduced tax. A cross-border will is the only reliable way to make both systems follow the same plan.

How to set up a cross-border will: step by step

1. List every asset and where it sits. Homes, bank and brokerage accounts, pensions, life insurance, business interests. Note which country each is in and how it is titled. Pensions and many US accounts pass by beneficiary nomination, not by will.
2. Settle each spouse's tax status. Citizenship, UK long-term residence, domicile under general law and treaty domicile drive the tax. Get this right before drafting.
3. Decide on one will or two. Use the table above. Where there is US real estate or a large US account, two wills is usually the practical choice.
4. Draft the wills together. Each will should name its assets, revoke only what it replaces and refer to the other by date. Use advisers who will read both documents.
5. Plan the spouse gifts for tax. Consider a QDOT for a non-US-citizen spouse where US estate tax could arise, and model the UK spouse exemption cap and the long-term residence election.
6. Choose executors who can act. A local executor in each country can save months. Make sure each knows where the other will is kept.
7. Sign each will correctly. Follow the signing and witnessing rules of the place where each will is signed. Do not use your spouse or anyone who benefits as a witness.
8. Review after life events. Marriage, divorce, a move between countries, a property sale or a change in residence status. Review both wills at the same time.

What people get wrong about a cross-border will

• Assuming a US will stays valid after marrying in England. Marriage cancels an English will made before it. If English law governs the succession, an old US will may be treated the same way.
• Using a will-writing template for the second will. Template wills almost always revoke all earlier wills.
• Leaving everything to a foreign spouse without checking the tax. The US marital deduction and the UK spouse exemption both shrink when the survivor is foreign.
• Forgetting non-will assets. UK pensions, US 401(k)s and IRAs, and life insurance usually pass by nomination. A will does not change them.
• Treating the will as the whole plan. Lifetime gifts, trusts and how assets are owned often matter more. Our guide to US UK trust and estate tax planning covers those tools.

How we help with a cross-border will

US/UK Cross Border Tax is US CPAs and UK tax advisers working as one team, with offices in London, Manchester, New York and San Francisco. We do not draft wills ourselves. We work with your lawyers in each country on the tax side of a cross border will US UK plan: residence and domicile status, the spouse exemption cap and election, QDOT planning, the estate tax treaty and US gift tax returns. Families with homes and accounts in both countries can read more on our page for cross-border families.

If you are writing new wills, have moved since your last ones or have just married, contact us to have the tax position reviewed before the documents are signed.