Divorce across two tax systems: the transfers that trigger a US bill

Figures relate to tax year 2025-26 (UK) / 2025 (US)

Splitting assets on divorce is usually tax-free in Britain. It is usually tax-free in America too. The exception catches exactly the couples this firm sees: an American married to a British spouse, dividing assets that America still taxes.

That exception can turn an ordinary settlement into a capital gains bill for one party. So this guide covers asset transfers, the family home, pensions and maintenance. It also covers the timing decisions that matter before anyone signs.

Key takeaways

• UK transfers between separating spouses are generally free of capital gains tax for three years.
• US law gives the same relief, but not where the receiving spouse is a non-resident alien.
• Maintenance paid under an agreement made after 2018 is neither deductible nor taxable in America.
• A UK court order does not split a 401(k) cleanly, and the wrong route creates a taxable distribution.
• Your filing status for the whole year depends on your position on 31 December.

What is the general rule on transfers?

Both countries try to keep tax out of a separation. Britain treats transfers between spouses as producing no gain and no loss. That treatment now runs for three tax years after the year of separation. Transfers forming part of a formal agreement can qualify for longer.

America has its own version for transfers between spouses or incident to divorce. According to the IRS guidance on divorced or separated individuals (opens in a new tab), those transfers generally produce no taxable gain. The receiving spouse takes over the original cost.

Both systems protect the separation. Only one of them checks the passport of the person receiving the asset.

Why does a non-American spouse change everything?

Because the US relief stops at the border. Where the spouse receiving the asset is a non-resident alien, the transfer falls outside the rule. America then treats that spouse as selling the asset at market value, and taxes the whole gain.

Picture a couple dividing a share portfolio. In Britain the transfer passes free of capital gains tax. In America the same transfer produces a taxable disposal for the US spouse, who receives nothing in cash to pay the resulting bill.

In our practice this is the single most expensive feature of a cross-border divorce. It rarely appears in the negotiation, because neither solicitor is looking at the American rules.

What happens to the family home?

Britain usually protects it through private residence relief, provided the departing spouse meets the conditions. America offers its own exclusion, at $250,000 of gain for a single filer and $500,000 for a couple filing jointly.

The timing decides how much of each applies. A spouse who moves out years before the sale can lose part of the relief in both systems, though special rules soften the British position where the former partner still lives there.

Selling before the divorce completes sometimes preserves the larger American exclusion. That calculation is worth doing early, because the decision shapes the settlement itself.

How are pensions divided?

British pensions split through a pension sharing order, which moves a percentage into the other spouse's own pension. The money stays inside the pension system, so no immediate tax arises in Britain, and the treaty generally protects the position for an American holder.

American retirement accounts are harder. A 401(k) normally splits through a qualified domestic relations order, which is a creature of US law. A British court order does not automatically qualify, and a withdrawal made to satisfy the settlement can be a taxable distribution with penalties attached.

Our guide to US retirement accounts in the UK explains how those accounts behave from Britain. Where a settlement touches one, the order needs drafting with the American rules in mind from the start.

Is maintenance taxable?

Not under current rules on either side. For agreements made after 2018, America gives the payer no deduction and treats the recipient as receiving nothing taxable. Per the IRS guidance on alimony (opens in a new tab), older agreements can still follow the previous treatment.

Britain reached the same place by a different route, treating spousal maintenance as outside income tax. Child support is also neutral in both countries, so neither payment shifts the tax burden between the parties.

How should you sequence a cross-border divorce?

Work out the tax before you agree the numbers. A settlement in gross figures can leave one party carrying an unexpected bill. The order below keeps the American exposure visible while terms are still moveable:

1. List every asset with its cost, current value and legal owner.
2. Mark which assets carry large unrealised gains.
3. Identify which spouse is American for tax purposes, and which is not.
4. Model the US cost of each proposed transfer before agreeing it.
5. Check the timing against the three-year UK window.
6. Draft pension orders with both countries' rules in view.
7. Agree in writing who bears any tax the transfers create.

That last point matters more than any other. Where a transfer creates US tax, the settlement should say who pays it, rather than leaving one party to discover it the following April.

When should you take tax advice?

As early as possible, ideally before heads of terms. A divorce settlement is hard to reopen once a court approves it. Advice at that late stage can only explain the bill, never prevent it.

Most of our work here takes a few hours. It sits alongside the family lawyer rather than replacing them. The cost is small against the sums being divided.

Ask your solicitor to involve us early. A short call often changes which assets go where.

A worked example

Take an illustrative example. An American in Surrey divorces her British husband. The settlement gives him a share portfolio worth £400,000, bought years ago for £150,000.

Britain treats the transfer as producing no gain. America treats it as a sale at market value, so she faces US capital gains tax on £250,000 of growth. She receives no proceeds from which to pay it.

Selling the portfolio first and splitting the cash would have produced the same US tax, but with money available to settle it. Dividing different assets between them might have avoided the charge altogether.

What filing status applies afterwards?

Your position on 31 December governs the whole American year. A divorce finalised on 30 December makes you single for that year. One completed in January leaves you married for the year just ended, whatever the separation date.

Head of household may be available where a child lives with you for more than half the year. That status brings a larger standard deduction than filing separately. Test it before preparing the return.

Children bring their own questions. Our guide to the child tax credit abroad covers which parent claims the credit and what the refundable part is worth.

Does a divorce change your residence position?

It can, and people often miss it. One spouse frequently leaves the country during a separation. That move changes residence in both systems, and residence decides who taxes what. The party who moves often carries the bigger change.

A US spouse returning to America mid-divorce can find state tax arriving too. Our guide to US state tax for expats explains how states treat new arrivals.

Time the move and the settlement together. Weeks can matter here.

Separation without divorce

British rules start running from the year of separation, not from the divorce itself. So the three-year window can close while a couple is still negotiating.

America looks at your marital status on 31 December. A long separation without a divorce leaves you married for US purposes, which narrows the filing options.

Keep a record of the separation date. Both systems ask for it. A diary entry or a solicitor letter is usually enough evidence.

What about joint accounts and reporting?

Keep reporting until the accounts actually separate. An American spouse retains FBAR duties for any account they own or can sign on, including joint accounts still open during the proceedings.

Close or re-register those accounts as soon as the settlement allows. Reporting an ex-partner's account for years after separation is a common and avoidable irritation.

Mistakes and traps in a cross-border divorce

Most of these come from treating a divorce as a purely British matter. Each appears regularly in settlements we review after the event:

• Transferring appreciated assets to a non-American spouse without pricing the US tax.
• Assuming a UK court order can split a US retirement account.
• Agreeing net figures without saying who pays any American tax that arises.
• Missing the three-year UK window for no gain, no loss transfers.
• Overlooking the filing status test on 31 December.
• Leaving joint accounts open and unreported during long proceedings.

Where one spouse is not American, the wider position is worth reviewing too. Our guide to the non-resident alien spouse covers the elections that shape a mixed-nationality marriage.

Does the country of the proceedings matter?

For tax, less than people expect. America taxes its citizens on the transfers themselves, whichever court approves the settlement. Britain applies its own rules to assets and residence in the same way.

The choice of jurisdiction matters enormously for the division itself, which is a question for family lawyers. What we can say is that the tax analysis should sit alongside that advice rather than after it.

How US UK Tax Accountants helps

We price each proposed transfer in both systems, so the settlement reflects what each party actually keeps. Our treaty relief service covers the cross-border analysis, and we work alongside your family solicitor rather than replacing them.

In our practice the useful work happens before anyone signs heads of terms. We agree a fixed fee in writing before any work begins.

Get the tax view before you sign

If a divorce involves American and British assets, a review before agreement protects both parties from a surprise bill. Tell us what you are dividing and who is American. You can book a consultation and hear back within one working day.

Last reviewed 17 September 2026 by the US UK Tax Accountants Tax Team. This article is general information, not personal tax advice — speak to a qualified US/UK tax adviser about your own position.

For the neighbouring question, Married to a British spouse: the marital deduction trap in US estate tax walks through it in detail.