Expat Self Assessment: Filing a UK Tax Return When You Live Abroad

You need to file a UK Self Assessment return from abroad if you have UK income or gains that HMRC cannot fully tax at source, or if HMRC has sent you a notice to file. Being non-resident under the Statutory Residence Test does not, on its own, remove the obligation. The UK keeps taxing rights over many UK-source items regardless of where you live, and Self Assessment is the mechanism HMRC uses to collect that tax and to confirm your residence position for the year.

The most important point for expats is that your residence status changes what is taxable, not whether you file. A non-resident is generally taxable only on UK-source income and on UK land and property gains, while a UK resident is taxable on worldwide income and gains. If you left the UK part-way through 2026/27, you may also qualify for split-year treatment, which itself has to be claimed on the return rather than applied automatically.

If you are unsure whether you cross the line into needing a return, the safest approach is to check your residence position first using a Statutory Residence Test (RDR3, GOV.UK) calculation, then map each source of UK income against the triggers below.

You register for Self Assessment from overseas by telling HMRC the reason you need to file, after which HMRC issues a Unique Taxpayer Reference (UTR). If you have never filed before, you register as a new taxpayer; if you have an existing UTR from your time in the UK, you reactivate that record rather than registering again.

How you register depends on why you are filing. Someone with UK rental income typically registers as a non-resident landlord and for Self Assessment; someone with other UK income registers under the general Self Assessment route. The registration deadline matters: if you have a new source of taxable income or gains, you must notify HMRC by 5 October following the end of the tax year. For income arising in 2026/27, that means notifying HMRC by 5 October 2027.

Allow time for post. HMRC sends the UTR and activation details to a physical address, which can be slow to reach an overseas address, and you cannot file until the UTR has come through. Registering early in the tax year, rather than close to the filing deadline, avoids a last-minute scramble. As a cross-border specialist firm, we register clients, deal with HMRC correspondence and act as agent so post and online access run through us rather than an unreliable international postal chain.

Most expat returns are built from three parts: the SA100 main return, the SA105 UK property pages, and the SA109 residence page. You add other supplementary pages only where they apply to your particular income.

• SA100: the main tax return that every Self Assessment filer completes. It captures your personal details, totals and tax calculation, and is the spine the supplementary pages attach to.
• SA105: the UK property pages, used to report UK rental income and allowable expenses. This is the core form for non-resident landlords.
• SA109: the residence page, now headed 'Residence and foreign income and gains (FIG) regime etc' on the 2026 form. It is where you state your residence status, claim split-year treatment, claim the FIG regime where eligible, and flag entitlement to the personal allowance as a non-resident.
• SA102: employment pages, if you have UK employment or directorship income.
• SA106: foreign pages, used by UK residents to report overseas income and to claim Foreign Tax Credit Relief (non-residents generally do not report foreign income to the UK).
• SA108: capital gains pages, where UK gains are reported and reconciled with any 60-day property report already made.

The FIG (foreign income and gains) regime, which replaced the old non-domicile rules on 6 April 2025 and is now in its second year in 2026/27, gives eligible new UK residents up to four years of relief on qualifying foreign income and gains. It is claimed through the SA109, which is one more reason that page is central to cross-border returns.

Your residence status, any split-year treatment, and any FIG claim are all reported on the SA109 residence page rather than calculated automatically by HMRC. The return reflects the position; it does not decide it for you, so you need to settle your Statutory Residence Test result before you fill the form in.

If you were non-resident for the whole of 2026/27, the SA109 records that status and limits your UK tax to UK-source income and UK property gains. If you left or arrived part-way through the year, you may claim split-year treatment so the year is split into a UK part and an overseas part, with foreign income in the overseas part falling outside UK tax. Split-year treatment is not automatic; it must be claimed and you must meet one of the qualifying cases.

The remittance basis (HS264, GOV.UK) that non-domiciled individuals used to claim was abolished from 6 April 2025 and replaced by the residence-based FIG regime. For 2026/27 there is no remittance basis claim for new arrivals; eligible recent arrivers instead claim FIG relief on the SA109. Anyone with foreign income and gains untaxed under the old rules may still have transitional matters to report, which is exactly the kind of cross-border detail worth getting checked rather than guessed.

Double taxation relief stops the same income being taxed in full in both the UK and your country of residence, and Foreign Tax Credit (GOV.UK) Relief is the main mechanism for delivering it on a UK return. Where both countries tax the same income, you generally claim a credit in one country for tax paid in the other, with the credit capped at the lower of the two countries' tax on that income.

Which country gives the relief, and how much, is governed by the double tax treaty (GOV.UK treaty list) between the UK and your country of residence. Treaties allocate taxing rights source by source: for example, a treaty may give your country of residence sole taxing rights over a private pension, or may allow both countries to tax rental income with one giving credit relief. Because the treaty controls the outcome, two expats with identical income in different countries can have very different UK positions.

For a non-resident, the typical pattern is that the UK taxes the UK-source income first and your country of residence then gives credit for the UK tax. For a UK resident with overseas income, the SA106 foreign pages are used to report that income and claim Foreign Tax Credit Relief for the overseas tax suffered. Getting the treaty interaction right is where cross-border returns most often save real money, and where mistakes most often lead to double taxation; we model the treaty position as part of a fixed-fee return so the relief is claimed correctly the first time.

Non-residents usually cannot file through HMRC's free online service because that service does not support the SA109 residence page, and almost every expat return needs it. HMRC is explicit that the residence and FIG pages must not be sent as a PDF or other attachment to an online return, so there is no workaround within the free service.

That leaves three practical routes for an expat who needs the SA109. You can file a paper return, which is allowed but carries the earlier 31 October paper deadline. You can buy HMRC-recognised commercial software that supports the residence pages and file online yourself. Or you can appoint a tax agent, who files through professional software and can also manage your HMRC correspondence.

For most cross-border clients the agent route is the least painful: it keeps the later online deadline, removes the need to buy and learn software, and means someone is dealing with HMRC on UK time while you are in a different country and time zone.

For a 2025/26 return the paper deadline is 31 October 2026, the online deadline is 31 January 2027, and any tax owed is also due by 31 January 2027. The 2026/27 tax year you are living through now follows the same pattern one year later: paper by 31 October 2027, online by 31 January 2028, with tax due by 31 January 2028.

If your tax bill is large enough, you may also have to make payments on account: two instalments towards the following year's bill, due on 31 January and 31 July. Expats with UK rental profits are the group most likely to be drawn into payments on account, so it is worth knowing they may apply before the cash is needed.

Paying HMRC from abroad is usually done by international bank transfer to HMRC's account, using your UTR as the reference. International transfers can take several working days to clear, and the payment must reach HMRC by the deadline rather than merely be sent by it, so initiate payment early. Faster Payments, debit card and other domestic methods are available if you still hold a UK bank account.

Filing late triggers an automatic £100 penalty straight after the deadline, and this applies even if you owe no tax or have already paid in full. The penalties then escalate the longer the return stays outstanding, so an overlooked deadline can become expensive quickly.

• Immediately after the deadline: a fixed £100 penalty, regardless of whether any tax is due.
• After 3 months: daily penalties of £10 per day for up to 90 days, a maximum of £900, on top of the £100.
• After 6 months: a further penalty of 5% of the tax due or £300, whichever is greater.
• After 12 months: another 5% of the tax due or £300, whichever is greater.

Paying late is penalised separately. Late payment penalties of 5% of the unpaid tax apply at 30 days, 6 months and 12 months, and HMRC also charges interest on the outstanding amount from the due date until it is paid. You can appeal a penalty if you have a reasonable excuse, but distance and unfamiliarity with the system are not reliable excuses, so the practical answer is to register early and file on time. If a deadline is genuinely at risk, getting an agent involved before it passes is far cheaper than the penalties that follow.

You register for Self Assessment from abroad by telling HMRC why you need a return, and the deadline is 5 October after the end of the tax year in which the new income or gain first arose (GOV.UK). If your first year with UK tax to report was 2025/26, that means notifying HMRC by 5 October 2026; if the income first arises in 2026/27, you have until 5 October 2027. Telling HMRC late is a failure to notify rather than a late return, and because the penalty is geared to tax still unpaid at the following 31 January it is usually nil if you pay in full by then, but do not lean on that: register as soon as you know a return is due.

• Online: HMRC's registration service is the default route, but it requires a verified Government Gateway or GOV.UK One Login sign-in, which is exactly where overseas applicants tend to get stuck.
• Paper: if you are not self-employed you can complete form SA1, print it and post it to HMRC, and the form accepts an address outside the UK (GOV.UK).
• Phone or agent: you can call HMRC's Self Assessment helpline from abroad for help with registration, or appoint an agent to register for you and take over the correspondence.

Expect the online identity checks to be the sticking point. Verification leans on a UK footprint, such as a UK address history and UK credit records, so people registering with an overseas address often cannot pass (LITRG). The GOV.UK ID Check app can sometimes bridge the gap if you hold a biometric passport, but if verification keeps failing, switch to the paper or phone route rather than retrying; as agents we register clients ourselves, so the identity hurdle never blocks the return.

Build in postal time. HMRC says you will usually get your Unique Taxpayer Reference by post around 15 days after registering and that it takes longer if you live overseas (GOV.UK); in practice, allow several weeks for the UTR and any online activation codes to reach an overseas address, and use any activation code as soon as it arrives, because codes expire a few weeks after the date on the letter. You cannot file until the UTR arrives, so registering early in the year rather than in the autumn keeps the deadlines comfortable.

Finally, registration only gets you a UTR; it does not mean you can file through HMRC's free online service. HMRC's own online filing cannot be used if you lived abroad as a non-resident, which is exactly what the SA109 residence pages cover (GOV.UK), so settle your filing route when you register: commercial software, due by 31 January after the tax year, or a paper return, which must reach HMRC by 31 October. For 2026/27 that means paper by 31 October 2027 or software by 31 January 2028.

Making Tax Digital timing for expats is the other date to pin down when you register. MTD for Income Tax started on 6 April 2026 for people whose qualifying income, meaning gross self-employment turnover plus gross property income before expenses, was over £50,000 in 2024/25, with the £30,000 wave following from 6 April 2027 (judged on 2025/26 income) and the £20,000 wave from 6 April 2028 (judged on 2026/27 income) (GOV.UK). Anyone whose 2024/25 return included the SA109 residence pages is automatically exempt until April 2027, and those who expect to file an SA109 for 2025/26 or 2026/27 can apply to HMRC for the same deferral (CIOT). Our full guide, Making Tax Digital for non-resident landlords, covers the quarterly deadlines, software options and exemptions in detail.