The short answer: a five-year on-ramp before worldwide taxation
Japan taxes long-term residents on worldwide income at some of the highest marginal rates in the developed world, but not from day one. A foreign national whose aggregate stay is five years or less within the preceding ten is a non-permanent resident: taxed in full on Japan-source income, but on foreign-source income only to the extent it is paid into Japan or remitted there. For a UK leaver with rental income, dividends or a pension at home, that five-year window is the corridor's most valuable feature.
The deciding factor for your UK bill is not your Japanese visa or your Tokyo apartment. It is the UK Statutory Residence Test (HMRC's RFIG20000 guidance, GOV.UK), which decides, year by year, whether the UK can still tax your worldwide income. Break residence, claim split-year treatment where you leave mid-year, and deal with what stays UK-taxable regardless; the Japanese position then takes over.
Breaking UK residence: the Statutory Residence Test
The SRT is applied in order: first the automatic overseas tests (which make you non-resident), then the automatic UK tests (which make you resident), then the sufficient ties test if neither is conclusive. For a move to Japan for work, the third automatic overseas test is the natural target.
- First automatic overseas test: UK resident in one or more of the previous three tax years and fewer than 16 UK days in the current year.
- Second automatic overseas test: not UK resident in any of the previous three tax years and fewer than 46 UK days.
- Third automatic overseas test (the usual route for movers): full-time work abroad across the tax year, broadly at least 35 hours a week with no significant breaks, fewer than 91 UK days and no more than 30 UK workdays.
A Japanese secondment on normal full-time hours fits the third test comfortably, provided you police the UK day counts: a fortnight back for a UK project plus Christmas and a summer visit, and the 30 UK workday limit goes before the 91-day limit does. If you cannot meet an automatic overseas test, the sufficient ties test combines your UK day count with the ties you keep (family, accommodation, work, a 90-day prior-presence tie and, for recent leavers, a country tie). Model your position with our SRT calculator at /tools/srt-calculator before you commit to a travel pattern.
Split year, the P85 and your final tax return
Where the conditions are met, split-year treatment divides the tax year into a UK part (taxed on worldwide income) and an overseas part (taxed only on UK-source income), so your Japanese salary after the split date is outside UK income tax for that year. For a secondee the usual gateway is starting full-time work overseas, meeting the third automatic overseas test from your start date to the end of the tax year with pro-rated day limits. Ceasing to have a UK home is the common alternative for a permanent move.
The admin is the same as for any departure. File a P85 (GOV.UK) if you are employed or have a pension and are not filing a return; if you are in Self Assessment, the departure-year return does the work instead. Split-year treatment is claimed on the SA109 residence pages, which cannot be filed through HMRC's own free online service, so you will generally need commercial software or an agent. Keep records of flights, work patterns and accommodation: residence questions are evidenced after the fact.
What the UK keeps taxing after you go
Becoming non-resident does not switch off UK tax on UK-source income. The Japanese twist is the right-hand column: as a non-permanent resident, much of that income only enters the Japanese net if you bring it to Japan.
| Income or gain | UK position after you leave | Japan position in your first five years (non-permanent resident) |
|---|---|---|
| UK rental profits on a kept property | UK-taxable; [Non-Resident Landlord Scheme](/guides/non-resident-landlord-tax) withholding unless HMRC approves gross payment | Foreign-source: taxed only if paid into or remitted to Japan, with treaty credit where it is |
| Gains on UK property | NRCGT: report and pay within [60 days](/guides/cgt-60-day-reporting-non-residents); 18% or 24% after the £3,000 annual exempt amount | Generally outside Japanese tax unless remitted; the treaty lets the UK tax UK land in any case |
| UK government service pensions | Remain UK-taxable (treaty Article 18) | Outside Japanese tax unless you are a Japanese national resident in Japan |
| Other UK pensions | Article 17 gives Japan sole taxing rights, but Article 4(4) limits UK relief to amounts remitted to Japan | Taxed only to the extent paid into or remitted to Japan while non-permanent resident; fully taxable after five years |
| UK dividends and interest | Depends on the treaty and the disregarded-income rules; take advice | Foreign-source: taxed only if remitted while non-permanent resident |
| Salary for work physically done in Japan | Outside UK tax once residence is broken and split-year applies | Japan-source: 5% to 45% national rates plus surtax and 10% inhabitant tax |
| Worldwide estate on death | IHT tail of up to 10 years for long-term UK residents | Japan's inheritance tax has residence and nationality based scope; take local advice early |
Three further UK rules deserve their own line. First, the temporary non-residence trap: if you were UK resident in at least four of the seven tax years before leaving and return within five years, gains and certain income realised while abroad can be taxed in your year of return (HMRC's CG26500 guidance, GOV.UK). A three-year secondment is well inside that window. Second, the residence-based IHT rules: a long-term UK resident's worldwide estate stays within UK inheritance tax for up to 10 years after leaving, and Japan's own inheritance tax can overlap with it. Third, voluntary National Insurance: apply on form CF83 to keep paying Class 2 or Class 3; a full UK State Pension is cheap to protect and expensive to rebuild.
Japan's residence tests and the non-permanent resident regime, verified
Japan draws its residence lines differently from the UK. You are a resident if you have a jusho (a domicile, broadly your principal base of life) in Japan or maintain a temporary place of abode there for a year or more; everyone else is a non-resident, taxed only on Japan-source income, with non-resident employment income charged at a flat 20.42% on the gross. Residents split into two classes: a Japanese national, or a foreign national whose aggregate stay exceeds five years within the preceding ten, is a permanent resident taxpayer, taxed on worldwide income; a foreign national at five years or less is a non-permanent resident (PwC Worldwide Tax Summaries: Japan).
The non-permanent resident rule is the corridor's centrepiece: Japan-source income is taxed in full, foreign-source income only to the extent it is paid in Japan or remitted there. In practice a UK leaver can keep UK rental profits, dividends and pension drawdown outside the Japanese net for up to five years by having them paid to, and left in, accounts outside Japan. The mechanics are less forgiving than they sound: foreign income paid into a Japanese account counts as paid in Japan, so the account structure needs setting up before you land, not after.
The clock runs on aggregate presence across the preceding ten years, so earlier stints in Japan count. Past five years, worldwide income is in scope: decide whether Japan is a posting or a permanent home before you go.
Japan's rates: national tax, surtax and the inhabitant tax
National income tax is progressive across seven brackets, from 5% on the first JPY 1.95 million of taxable income to 45% above JPY 40 million, with a 2.1% surtax (the special reconstruction income tax) applied to the national tax bill. On top sits the local inhabitant tax at a flat 10% of prior-year income, charged to anyone resident in Japan on 1 January, taking the combined top marginal rate to a little under 56%. Your first calendar year generally carries no inhabitant tax, because you were not resident the previous 1 January (PwC Worldwide Tax Summaries: Japan).
Investment income is gentler than the headline rates suggest: interest, dividends from listed companies and gains on listed shares are generally taxed separately at a flat 20.315% (15.315% national including surtax, plus 5% inhabitant tax).
The honest boundary: Horizon advises on the UK side and coordinates with a local adviser or zeirishi in Japan. Your Japanese registrations, year-end adjustment and returns belong with local counsel.
The exit tax: the long-stayer's problem at the far end
Japan operates an exit tax on long-stayers leaving with substantial financial assets. It applies where two conditions are met at departure: in-scope financial assets (broadly securities, investment trusts and unsettled margin and derivative positions; cash and real estate are outside it) worth JPY 100 million or more, and more than five years of residence in aggregate within the preceding ten. Meet both and you are treated as having sold those assets at market value on the day you leave, with tax at roughly 20% on the unrealised gains; payment can be deferred for up to ten years with the right filings and collateral, and the charge unwinds if you return still holding the assets (RSM Shiodome: Japan's exit tax system).
For UK movers the practical points are three. First, a five-year posting sits outside the exit tax by construction; it is the open-ended move that walks into it, and periods under certain working visa statuses may be excluded from the five-year count, so the visa history needs checking locally. Second, the threshold is measured against your whole portfolio, including UK ISAs and dealing accounts you never touched from Japan, and residents above the same line face annual asset reporting (PwC Worldwide Tax Summaries: Japan, tax administration). Third, sequence it against the UK's temporary non-residence rule on your return: two deemed-taxation regimes on the same portfolio is exactly what advice exists for.
The 2006 UK-Japan treaty and the pension question
The 2006 UK-Japan Double Taxation Convention entered into force on 12 October 2006 and has had effect in the UK since 6 April 2007 for income tax and capital gains tax, amended by a 2013 protocol in force from 12 December 2014 and modified by the Multilateral Instrument (GOV.UK). The residence tie-breaker settles dual-residence years, UK land gains stay taxable in the UK under Article 13, and dividend withholding is capped at 10%.
The pension articles are where this treaty earns close reading. Article 17 provides that pensions beneficially owned by a resident of a contracting state are taxable only in that state: once resident in Japan, your UK personal and occupational pension income is, on the face of it, Japan's alone to tax, and an NT code can take UK PAYE off the payments. Article 18 carves out government service pensions, which stay taxable only in the UK unless you are both resident in and a national of Japan.
Then comes the clause most people miss. Article 4(4) is a limitation of relief provision: where the UK reduces or exempts tax under the treaty, and Japan taxes you only on the part of that income remitted to or received in Japan, the UK relief applies only to the amounts actually remitted. A non-permanent resident drawing a UK pension into a UK bank account and leaving it there is precisely in that position, so the unremitted pension income can remain UK-taxable despite Article 17. Sometimes remitting the pension and taking Japanese rates is cheaper, sometimes leaving UK tax running for the five-year window is fine, and double tax relief tidies up whatever overlap remains. Treaty claims run through the SA109 and HMRC's DT-Individual process, so keep the paperwork tidy from year one.
Who the move genuinely suits, and how Horizon helps
Japan suits secondees and employed professionals on defined postings, who get split-year treatment on the way out, the non-permanent resident shield on their UK income while there, and a clean exit before either the exit tax or worldwide taxation bites. It suits less well if they will pass the five-year mark with a large portfolio, if their income will be mostly Japan-source salary in the top brackets, or if they will return to the UK within five years with significant gains to realise. And Japan does nothing for UK property income and gains, which stay UK-taxable regardless.
Horizon UK Tax Solutions is a Chartered Tax Adviser practice that handles the UK side of this move: SRT planning, split-year claims, the departure-year return, NT codes on pensions, non-resident landlord filings and 60-day NRCGT reports. Fees are fixed and agreed upfront: personal tax returns from £350, non-resident and expat returns from £550, and complex cross-border work from £750. If a Japanese posting or a permanent move is on your horizon, book a free clarity call before you set a departure date, or read more on our expat tax adviser service page.
