Moving back to the US: the tax year that decides everything

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

Moving back to the us from Britain sounds simpler than leaving was. In tax terms it rarely is. You are unwinding a UK life while restarting a full American one, and the two calendars do not line up. The months either side of the flight decide which country taxes what.

Handled early, most of it is routine. Handled after landing, several doors have already closed. So this guide covers the timing that matters, the assets that behave badly on repatriation, and the state trap that greets people at the airport.

Key takeaways

• The UK tax year ends 5 April and the US year ends 31 December, so timing decisions cut both ways.
• Split-year treatment can end UK residence part-way through the year, but it must be claimed.
• Gains, bonuses and share vestings belong to whichever side of the move you place them on.
• ISAs lose their tax-free status the moment you are taxed as a US resident again.
• Your destination state may start taxing you from the day you arrive.

What changes when you move back?

Moving back to the us changes two things at once. Your UK residence usually ends, so HMRC stops taxing your worldwide income. And your American life restarts fully, which means state tax, domestic reporting and a return that no longer leans on expat provisions.

Federal filing itself never stopped, of course. According to the IRS guidance for citizens abroad (opens in a new tab), Americans file wherever they live. What changes is the shape of the return: no foreign earned income exclusion, fewer foreign tax credits, and a growing set of domestic questions.

Why does the timing matter so much?

Because the two tax years overlap awkwardly. Leave in February and you sit in one UK year and two US ones. Leave in May and the pattern shifts entirely. Each arrangement changes which country taxes a bonus, a gain or a pension withdrawal.

Timing also controls relief. UK residence ending mid-year may qualify for split-year treatment, so only part of the year gets taxed here. Our guide to the statutory residence test sets out how residence and split years actually work, and the conditions are strict.

Which assets behave badly when moving back to the us?

Some holdings are fine in Britain and awkward in America. Others are the reverse. The table below covers the ones that cause most of the trouble in practice, and each deserves a decision before the flight rather than after it.

Every asset you keep has an opinion about where you live. Ask them all before you book the removals van.

The ISA problem, in reverse

While abroad, an American in Britain already faced US tax on ISA funds under the punitive rules for foreign investments. Our guide to why your ISA is a US tax problem covers that side. Returning home does not fix it, and it removes the UK benefit too.

Once you resume US residence, the ISA is simply a taxable account with awkward reporting. So the decision is whether to unwind it while still here, or keep it and accept the reporting. There is no universally right answer, but there is a right answer for your numbers.

Pensions: the asset that rewards patience

UK pensions travel better than most holdings, because the treaty coordinates them. Growth inside a qualifying scheme can generally stay untaxed until drawn, and drawdowns are usually taxed where you live. That makes the pension one of the few assets you can safely leave alone.

The mistakes come from movement rather than stillness. Drawing a lump sum in the year of the move, or transferring the scheme offshore, can turn a protected position into a taxable one. Our guide to UK pensions and US tax covers the mechanics before you touch anything.

How do you plan the move properly?

Work backwards from the flight date, because almost every lever expires on arrival. Six months of runway is comfortable, three is workable, and the week before is mostly damage limitation. Here is the sequence we use with clients returning home:

1. Fix the intended departure date, then test whether split-year treatment applies to it.
2. List every asset and ask where each is taxed before and after the move.
3. Decide on the ISA, the house and any funds while UK rules still apply.
4. Map bonus and share-vesting dates against the departure, and move what you can.
5. Check the destination state's residency rules before choosing where to land.
6. Tell HMRC you are leaving and file the final Self Assessment return properly.
7. Set up US estimated payments for the first year, since withholding may not cover you.

Currency: the cost nobody budgets for

Moving back to the us means converting a life's savings across an exchange rate you do not control. A five percent swing on £200,000 is £10,000, which dwarfs most of the tax planning in this article. So treat the currency question as part of the move, not an afterthought.

There is a tax dimension too. Gains on foreign currency itself can be taxable to an American, and paying off a UK mortgage after the pound moves may create a reportable gain. Keep records of what you converted and when, because reconstructing it later is genuinely painful.

The state that greets you on arrival

Federal tax follows you everywhere, so the real variable is the state. Land in Texas or Florida and there is nothing to plan. Land in California or New York and residency generally begins the day you arrive, with worldwide income taxed from that point.

This cuts both ways with any income you realise near the move. A gain taken before arrival may escape state tax entirely, while the same gain a month later does not. Our guide to state tax for expats covers the residency rules from the departure side, and the same principles apply on return.

Leaving the UK cleanly

HMRC needs telling. You report the departure, file a final return covering the UK part of the year, and settle whatever remains due. Per GOV.UK's guidance on moving abroad (opens in a new tab), leaving without filing simply leaves the record open behind you.

Two threads often continue after departure. UK rental income keeps its own filing duty through the non-resident landlord rules. And UK pensions and property gains can stay within HMRC's reach for years. Neither is difficult, but both need setting up rather than assuming.

A worked example

Take an illustrative example. A dual filer plans to leave London for Boston in March 2026. She holds a stocks and shares ISA worth £90,000 and expects share options to vest that July, worth roughly $60,000.

Moving in March places the vesting after her return, so Massachusetts taxes it in full. Delaying the flight to August would place the vesting in her UK period instead, where different rules and credits apply. Meanwhile selling the ISA before departure removes years of awkward reporting, at a UK cost of nothing.

The mistakes and penalties that follow a rushed return

Errors made while moving back to the us cost money quietly, then surface the following April. These are the ones we unwind most often, and every single one was avoidable with a few months of notice:

• Flying first and planning afterwards, once every timing lever has already expired.
• Assuming split-year treatment is automatic when it must be claimed and justified.
• Keeping an ISA into US residence without deciding whether the reporting is worth it.
• Drawing a pension lump sum in the transition year, when its treatment is least certain.
• Landing in a high-tax state days before a large gain or vesting event.
• Never telling HMRC, so the UK record stays open and penalties accrue behind you.

The last one deserves emphasis, because it compounds silently. A missing final return still attracts the UK late-filing ladder, and our free late-filing penalty calculator shows how quickly £100 becomes far more. Distance does not pause those charges.

What about the first US return after you land?

It usually looks different from the ones you filed abroad. The exclusion disappears, foreign tax credits shrink, and state filing arrives. Withholding on a new salary rarely covers a year that also includes UK income, so a balance is common.

That first return also carries the reporting tail of your UK life. Accounts you still hold need declaring, and pensions continue to appear. In our practice we see the first post-return year cause more confusion than any year abroad, precisely because people expect it to be simple.

Budget for the transition rather than assuming it disappears. Keep the UK paperwork accessible for at least a year after landing, and expect one messy return before things settle. By the second year, most returning families are back to an ordinary domestic filing with a short foreign tail attached.

How US UK Tax Accountants helps

We plan repatriation as one project across both systems through our double tax treaty relief service. That covers the timing analysis, the asset decisions, the final UK return and the first American one afterwards.

One senior specialist holds both sides, so the UK exit and the US arrival are planned against each other rather than in sequence. Fees are fixed and agreed in writing before any work begins, and the planning conversation happens while the levers still exist.

Plan the move before you book the flights

If moving back to the us is on your horizon this year or next, the cheapest planning happens now. Tell us your assets and your intended timing. We will model the options, flag what to act on first, and quote a fixed fee in writing. Book a consultation and hear back within one working day.

Last reviewed 8 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.

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