Repatriating from the UK to the United States is a harder tax event than emigrating was, for a reason that is easy to miss: on arrival in Britain you were entering a system, but on departure you are leaving one system while re-entering another, and the two use different tax years, different residence tests and different definitions of almost everything. The decisions that determine the bill are made in the twelve months before you leave, not in the filing season afterwards. Get the departure date, the disposal sequencing and the income timing right and repatriation can be close to tax-neutral. Get them wrong and you can pay UK tax on gains you did not need to realise, lose foreign tax credits you spent years accumulating, hand an unexpected year to a US state you thought you had left, and still be inside the UK inheritance tax net for a decade.
The two clocks that never line up
The UK tax year runs from 6 April to 5 April. The US tax year is the calendar year. Every cross-border timing decision on repatriation is a decision about where a piece of income or gain falls relative to two boundaries that are three months and five days apart.
A bonus paid in February sits in one UK tax year and one US tax year. Move it to April and it sits in a different UK year but the same US year. Move it to January and the reverse. There is no arrangement that makes both boundaries convenient at once, which is why the exercise is about choosing which one matters more for the particular item — and that depends on the rates, the reliefs and the credits available on each side in each year.
This is also why generic repatriation advice is close to useless. The right answer for someone leaving in May is structurally different from the right answer for someone leaving in November.
Establishing the date you cease to be UK resident
UK residence is determined by the Statutory Residence Test, and leaving the country does not automatically make you non-resident from the day the plane takes off. The SRT works on days, ties, work patterns and accommodation, and someone who keeps a UK house, returns frequently for work, and has family remaining can remain UK resident for a full tax year after physically relocating.
Where the conditions are met, split-year treatment divides the tax year of departure into a UK part and an overseas part, so that foreign income and gains arising after departure escape UK tax. There are several distinct cases under which split-year treatment can apply — leaving to work full-time overseas, ceasing to have a UK home, and accompanying a partner among them — and each has its own conditions about work hours, UK day limits and the timing of when the UK home goes.
Do not assume it applies. Split-year treatment is a set of specific statutory cases, not a general principle of fairness, and falling outside all of them means the whole tax year is a UK resident year. Our guide to the Statutory Residence Test for Americans sets out how the counts work. HMRC's overview of what to do when you leave, including Form P85, is on GOV.UK.
The five-year rule that undoes clever timing
The temporary non-residence rules exist precisely to stop people leaving the UK for a short period, realising income or gains while non-resident, and returning. If you are non-resident for five years or fewer and then resume UK residence, certain income and gains arising during the period of non-residence can be taxed in the UK in the year of return.
For a genuine permanent repatriation this is irrelevant. For the very common case of an American going home for a two or three-year assignment with an open question about coming back, it is central — and it is frequently ignored because everyone involved is treating the move as permanent when the family is privately treating it as provisional.
The honest question to ask is not whether you intend to return but whether you might. If the answer is that you might, the planning has to survive that outcome, which usually means not realising large UK-taxable gains during the gap on the assumption they are safely outside the net.
Disposals: sequencing gains around the departure date
Capital gains are where sequencing pays for itself. As a UK resident you are taxable on worldwide gains; after ceasing to be resident, most gains fall outside UK CGT, with the significant exception of UK land and property, which remains within the UK charge for non-residents.
So a portfolio of non-UK assets standing at a large gain is generally better disposed of after residence has ceased, and a UK property is generally not improved by waiting. But the US side does not go away in either case — as a citizen or Green Card holder you are taxable on worldwide gains in every year regardless of where you live, so a gain moved out of the UK charge does not disappear, it simply loses the foreign tax credit that would have sheltered it.
That is the counter-intuitive point that catches sophisticated people. Realising a gain while still UK resident may produce UK tax that generates a US foreign tax credit, leaving little or no net additional cost. Realising the same gain the week after departure can produce a full US tax charge with nothing to credit against it. The right sequence depends on the relative rates and on whether you have credits available, not on a general preference for being outside the UK net.
The UK home, and the two exclusions that do not match
Selling the UK house is usually the largest single transaction of the move, and both countries have a relief for it that the other does not replicate.
The UK gives Private Residence Relief, which can exempt the gain on a main home entirely, subject to periods of occupation and absence. The US gives the section 121 exclusion, capped at $250,000 of gain for a single filer and $500,000 for a married couple filing jointly, subject to ownership and use tests. A gain fully relieved in the UK can therefore be substantially taxable in the US, because the UK relief is uncapped and the US one is not.
Layered on top is the currency problem. The US computes the gain in dollars using the exchange rate at purchase and at sale, so a property that gained modestly in sterling can show a large dollar gain if the pound strengthened over the ownership period — or the reverse. And if there is a sterling mortgage, repaying or refinancing it can produce a separate foreign currency gain taxable as ordinary income under section 988, with no UK equivalent and therefore no credit. Our guide to selling a UK home as a US citizen works through the mechanics.
Timing the sale relative to departure matters for a further reason: the US use test looks at occupation in the five years before sale, so a home sold long after you have moved out can fail it.
Foreign tax credits: use them or strand them
Most Americans in the UK end up with excess foreign tax credits, because UK effective rates on earned income generally exceed US ones. Those credits carry back one year and forward ten, within their separate income categories.
On repatriation, the tap turns off. Once you are living in the US and paying US tax on US-source income, you stop generating foreign taxes and you frequently have no foreign-source income to absorb the carryforwards against. Credits accumulated over a decade can expire entirely unused.
The planning response is to look for foreign-source income to soak them up in the years immediately around departure — which can mean deliberately accelerating a foreign-source item into the departure window, or being thoughtful about the categories the credits sit in. This is genuinely valuable and almost always overlooked, because the credits feel like a permanent asset right up until the point they lapse. Our comparison of the foreign tax credit and the FEIE explains the category rules, and you can model the position with our foreign tax credit calculator.
Note too that the Foreign Earned Income Exclusion — $132,900 for the 2026 tax year, as published by the IRS — is pro-rated in the year of return, because it depends on qualifying days abroad. If you have been relying on the FEIE rather than credits, the departure year exclusion will be a fraction of the headline figure.
The state that is waiting for you
Federal tax is only half the US picture, and the state half behaves very differently. Some states take the view that a person who left for an overseas posting never abandoned domicile at all, and will assess every year of the absence if they can. Others are straightforward about it. The difference between them is worth a great deal of money.
On the way back, the question is which state you become resident in and on what date. Arriving on 20 December rather than 5 January can hand a state an entire additional year of your income, including any large repatriation-related items. States apply their own residency tests, their own part-year rules and their own treatment of foreign income — and most give no credit for foreign taxes at all, which means UK tax paid on income a state also taxes is simply lost.
Our guide to state tax for Americans abroad covers which states are aggressive and what abandoning domicile actually requires. The practical rule on return is to decide the destination state's start date deliberately rather than letting the moving company decide it.
Pensions: the decisions you cannot easily reverse
UK pension pots do not have to be moved and usually should not be moved in a hurry. A SIPP or workplace scheme can remain in the UK and be drawn from the US, with the US/UK treaty allocating taxing rights over the eventual payments and giving the 25% tax-free lump sum its own contentious treatment.
Transferring to a US arrangement is rarely straightforward and can be actively harmful, and transfers to overseas schemes can carry UK charges. The point to grasp is that this is a decision with a long tail and no easy reversal, so it should not be taken in the last fortnight before a move because someone suggested consolidating everything.
Contributions are the more urgent item. UK tax relief on pension contributions is available while you have UK relevant earnings, and that window closes on departure. If there is unused annual allowance and the cash is available, the final UK tax year is often the last chance to use it — subject to the US treatment, which does not always mirror the UK relief. Our guide to US tax on UK pensions and SIPPs covers the mismatch.
ISAs, funds and the PFIC clean-up
ISAs were never tax-free from the US perspective, and repatriation is the natural moment to deal with them. A UK-domiciled fund or investment trust held inside an ISA is a passive foreign investment company for US purposes, and if it has been sitting under the default section 1291 regime it has been accruing an interest charge on deferred distributions the whole time.
The question on departure is whether to dispose before or after ceasing UK residence. Disposing while UK resident may produce UK tax that generates a credit; disposing after may produce a clean US charge with nothing to credit. But PFIC gains sit in their own category for foreign tax credit purposes, which frequently means the UK tax paid cannot shelter the US charge anyway.
Whichever way it falls, arriving in the US still holding a portfolio of UK funds is the worst outcome, because the reporting obligation and the punitive regime follow you and there is no longer any UK tax being paid to offset it. Our guide to PFIC rules and UK ISAs sets out the elections available.
The inheritance tax tail follows you home
This is the item most repatriating Americans have never heard of. Since 6 April 2025 the UK charges inheritance tax on the basis of residence rather than domicile, and someone who has been UK resident for at least ten of the previous twenty tax years is a long-term resident whose worldwide estate is within the UK charge at 40%.
Leaving does not end it. A tail provision keeps long-term residents inside the net for three years where UK residence was ten to thirteen years, rising by one year for each further year of residence to a maximum of ten. So an American who spent twelve years in London and moved back to Boston remains exposed to UK inheritance tax on their entire worldwide estate for three more tax years, while also being inside the US estate tax system.
If you are approaching but have not yet passed the ten-year threshold, the departure date is not merely a convenience — it is the single highest-value decision in the whole move. Our guide to the long-term resident test and its ten-year tail covers the arithmetic.
The Temporary Repatriation Facility, if it applies to you
For former remittance-basis users there is a closing window worth checking before you go. The Temporary Repatriation Facility allows pre-6 April 2025 foreign income and gains to be designated and brought into the UK at 12% for 2025-26 and 2026-27, rising to 15% for 2027-28, after which it ends.
Whether it is worth using on the way out depends on whether those funds would otherwise be trapped by the remittance rules and on what you intend to do with them. Someone leaving permanently and never remitting may have no need of it at all. Someone who may return, or who has UK expenditure to fund, may find 12% a good price for permanently cleansing a mixed fund. Our guide to the TRF deadline covers the mechanics.
Final-year filings on both sides
The administrative tail of a move is longer than people expect, and it is where otherwise good planning quietly goes wrong.
On the UK side there is Form P85 or a final Self Assessment return, a possible PAYE refund if you leave part-way through the tax year, and continuing UK obligations if you keep UK property or receive UK-source income as a non-resident. On the US side there is the departure-year return with its part-year FEIE, the foreign tax credit computation, and the final-year FBAR — which is still required for the year in which the UK accounts were open, filed the following year, long after you have moved.
Closing UK bank accounts before the year end does not remove the FBAR obligation for that year, and the aggregate threshold is tested on the highest balance during the year, which is often high in a moving year because of a property sale. This is a common and entirely avoidable late filing.
- File Form P85 or a final Self Assessment return with HMRC
- Reclaim any overpaid PAYE for the partial UK year
- File the final-year FBAR even though the accounts have since closed
- Keep UK completion statements, SDLT certificates and trustee records permanently
- Update the IRS and Social Security with the new address before the first US filing season
- Establish the state residency start date deliberately and document it
A twelve-month timeline
- T-12 months — establish your UK tax year count for inheritance tax purposes and decide whether the departure date needs to move.
- T-9 months — model the disposal sequence for investments and the UK home against both tax systems, including foreign tax credit availability.
- T-6 months — decide the split-year case you will rely on and align the departure date, home sale and work pattern with its conditions.
- T-6 months — use remaining UK pension annual allowance if the US treatment supports it.
- T-3 months — deal with ISAs and PFIC holdings; do not carry them across.
- T-3 months — fix the destination state and the arrival date; get advice if it is an aggressive domicile state.
- T-1 month — file P85 groundwork, gather trustee and broker records, and record account balances for the final FBAR.
- T+3 months — reconcile the foreign tax credit carryforward position and identify anything at risk of lapsing.
Why this is worth doing properly
Repatriation is one of a small number of moments where the whole of a cross-border position is in play at once — residence, gains, credits, pensions, property, estate exposure and state tax, all moving together and all sensitive to the same handful of dates. Very little of it can be fixed retrospectively. A gain realised in the wrong tax year is realised. A credit that has expired has expired. A tenth year of UK residence, once completed, cannot be uncompleted.
It is also, in our experience, the point at which people are least inclined to get advice, because the move itself is consuming all their attention and the tax feels like something to sort out later. Later is after the decisions have been made.
If you moved in the other direction with proper planning — and our guide to pre-immigration tax planning for the UK sets out what that looks like — the return journey deserves the same treatment. It is generally the more expensive of the two.
