UK Self Assessment: A Guide for Expats and Non-Residents
UK Self Assessment is the tax return system used by individuals who cannot have all their tax collected at source through PAYE. For expats, non-residents, and those with foreign income, Self Assessment is often required regardless of whether any UK tax is ultimately owed. Getting registered, filing on time, and completing the non-resident pages correctly is essential to avoid automatic HMRC penalties.
Who must file a UK Self Assessment return
You must file if you: are self-employed with income over £1,000; are a company director; have income from UK property rental; have income from savings over £1,000 (basic rate) or £500 (higher rate); have foreign income that must be reported to HMRC; have income over £100,000; received child benefit and either you or your partner earned over £60,000 (the High Income Child Benefit Charge); or have been sent a notice to file by HMRC. Non-residents with UK-source income must file even if their UK income is small.
UK Self Assessment deadlines for 2025
The UK tax year runs from 6 April to 5 April. For the 2023/24 tax year (6 April 2023 to 5 April 2024): paper return deadline was 31 October 2024; online return deadline is 31 January 2025; tax payment deadline is 31 January 2025; first payment on account for 2024/25 is also due 31 January 2025; second payment on account is due 31 July 2025. For the 2024/25 tax year (filed in 2025/26): online return due 31 January 2026.
Late filing penalties
HMRC imposes automatic penalties for late Self Assessment returns: £100 immediately if the return is not filed by the deadline (even if no tax is owed); a further £10 per day after 3 months (up to 90 days, maximum £900); an additional £300 or 5% of tax due (whichever is higher) after 6 months; and another £300 or 5% after 12 months. These penalties apply regardless of whether you owe any tax, a nil return filed late still triggers the £100 penalty.
Non-resident Self Assessment: the SA109
Non-residents filing a UK Self Assessment must complete the SA109 supplementary pages, which deal with residence status, split-year treatment, and the Statutory Residence Test. SA109 is not available through HMRC's online filing system, you must use third-party software (or paper filing) to include SA109. This catches many non-residents off guard when they try to file themselves online. Our UK filing packages handle SA109 correctly.
Payments on account
If your Self Assessment tax bill is over £1,000, HMRC requires payments on account, advance payments toward next year's bill. Each payment on account is half your current year's bill, due January 31 and July 31. New filers are often shocked to receive a bill in January that is 150% of expected (one year's tax plus the first payment on account). We explain this as part of onboarding so there are no surprises.
Our licensed CPAs and qualified accountants handle your filing from start to finish, applying all relevant exclusions, credits, and treaties.
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Frequently asked questions about UK Self Assessment: A Guide for Expats and Non-Residents
I live abroad but have UK rental income, do I need to file Self Assessment?
Yes. Non-residents with UK rental income must file a UK Self Assessment return, completing the property pages (SA105) and the non-resident pages (SA109). You should also consider applying to HMRC under the Non-Resident Landlord scheme to receive rental income gross.
What is the January 31 Self Assessment deadline?
31 January is the deadline for submitting your online Self Assessment return for the previous tax year (ended 5 April) and for paying the tax owed. Both the filing and the payment are due on the same date. Paper returns are due earlier, 31 October.
Can I file Self Assessment online if I'm non-resident?
You can use HMRC's online service only if you don't need the SA109 non-resident supplementary pages. Since most non-residents do need SA109, you'll typically need to use commercial software or paper filing. Our service handles this for you.
What is the SA109 form?
SA109 is the supplementary pages of the UK Self Assessment dealing with residence, remittance basis, and overseas income. It's required if you're claiming non-resident status, split-year treatment, or remittance basis. SA109 is not included in HMRC's own online filing service.