Why You Cannot File Your Non-Resident Tax Return on HMRC's Website

No. HMRC's free online Self Assessment service handles the main SA100 return and the most common supplementary pages, such as employment, self-employment and UK property. It does not support the SA109, the residence pages. GOV.UK lists the exclusions from the online service directly, and living abroad as a non-resident is one of them. The official guidance for non-residents is equally blunt: you cannot use HMRC's online services to report your income, and it points you to paper filing, commercial software or a tax professional instead.

This is not a temporary outage or a processing backlog. The SA109 has been outside the scope of HMRC's own online service for many years, and HMRC has not published any timetable for adding it. It is best understood as a long-standing design limitation: HMRC built its free service for the mainstream domestic filer and has left the more complex residence cases to the commercial software market and to agents. Whatever the reason, the practical effect is the same every year: the people with the most complicated residence positions are the ones locked out of the free filing route.

One thing that has changed recently is the form itself. From the 2025/26 tax year the SA109 is titled "Residence and foreign income and gains (FIG) regime etc", reflecting the regime that replaced the remittance basis for foreign income and gains arising from 6 April 2025. The name is new; the online filing gap is not.

The SA109 is where your residence position is formally declared and where residence-based claims are made. You will generally need it if any of the following applies for the tax year:

• You were non-UK resident under the Statutory Residence Test and need to declare that status, claim a personal allowance as a non-resident, or claim relief under a double taxation agreement.
• You are claiming split-year treatment because you left the UK or arrived in the UK part-way through the tax year, so only part of the year is taxed as a UK resident.
• You are claiming the 4-year FIG regime, available from 6 April 2025 to people in their first four years of UK residence after at least ten consecutive tax years of non-UK residence. The claim is made on your Self Assessment return, and claiming it costs you your Personal Allowance and Capital Gains Tax annual exempt amount for that year.
• You have legacy remittance basis matters, for example remittance basis claims for years before 2025/26 or foreign income and gains from earlier years that you have now remitted to the UK.
• You are dual resident and claiming treaty residence in another country.

The classic victim is the first-year-abroad filer. You leave the UK in, say, August, keep a rental property or some UK income, and sit down the following autumn to file the return you have always filed through your HMRC online account. This year, for the first time, you need split-year treatment, which lives on the SA109, and the account you have used for years cannot file it. Many people discover this in December or January, after the paper deadline has long passed. If you are unsure of your residence position for the year, our SRT calculator is a good place to start, and our guide to the Statutory Residence Test explains the rules in full.

GOV.UK gives non-residents three routes, and each comes with its own deadline and trade-offs. For the 2025/26 tax year (6 April 2025 to 5 April 2026), the dates are as follows.

Option one: file the whole return on paper. You complete the SA100, the SA109 and any other supplementary pages by hand or as printed PDFs and post them to HMRC. The catch is the deadline: HMRC must receive a paper return by 11:59pm on 31 October 2026, three months before the online deadline. Filing on paper also means no automatic tax calculation at the point of filing, slower processing, and postal risk, which is a real consideration if you are mailing a return from Singapore or Sydney in late October.

Option two: buy commercial software that supports the SA109. HMRC maintains a list of recognised Self Assessment software suppliers, and some products for individuals include the residence pages, which GOV.UK notes may appear as a "residence" or "remittance basis" section. Filing through software counts as online filing, so the deadline is 11:59pm on 31 January 2027. The trade-offs: you pay for the product, not every product supports every supplementary page (check before you buy), and the software fills in boxes rather than answering the harder question of what your residence position actually is.

Option three: use an agent. Tax advisers file through professional software that includes the SA109 as standard, so the normal 31 January 2027 deadline is preserved. The real value is usually not the filing mechanics but the judgement behind the boxes: confirming your Statutory Residence Test outcome, choosing the right split-year case and dates, and checking whether a treaty claim or a FIG claim actually leaves you better off. See our guide to expat Self Assessment for what a non-resident return involves end to end.

Whichever route you choose, the payment deadline does not move: any tax due for 2025/26 must be paid by 31 January 2027, along with the first payment on account for 2026/27 if one applies.

Everyone knows 31 January as the Self Assessment deadline. Far fewer people know that it only applies to online returns. A paper return, which is the default route for anyone who needs the SA109 and does not buy software or appoint an agent, must reach HMRC by 31 October. That is the trap: the filers forced onto paper are precisely the ones who assume they have until January.

Miss the deadline and the penalties are automatic and grow quickly, even if you owe no tax at all:

• 1 day late: an initial £100 fixed penalty.
• 3 months late: daily penalties of £10 per day, up to a maximum of £900.
• 6 months late: a further penalty of 5% of the tax due or £300, whichever is greater.
• 12 months late: another 5% or £300, whichever is greater.

That is a minimum of £1,600 after a year, before any tax-geared uplift. Late payment is penalised separately: 5% of the unpaid tax at 30 days, again at 6 months and again at 12 months, plus interest throughout. You can appeal a penalty if you have a reasonable excuse, but relying on an appeal is not a filing strategy.

Two more dates matter for first-year leavers. If you have never filed a return before, or did not need to file for 2024/25, you must tell HMRC by 5 October 2026 that you need to complete one for 2025/26; register later and HMRC will set you a bespoke deadline three months from the date on its letter or email. And remember the paper deadline is a receipt deadline, not a posting deadline: HMRC must have the return by 11:59pm on 31 October 2026, so international post needs a generous buffer.

First, the good news: missing 31 October does not mean you have already incurred a penalty. The 31 October deadline applies only to returns filed on paper. If you have not yet filed at all, simply do not file on paper. Switch to an online route, either commercial software that supports the SA109 or an agent, and file by 31 January 2027. File online by that date and no late-filing penalty arises.

What you should not do is post a paper return in November or December. A paper return received after 31 October is late the moment it arrives, even though the online window is still open, and the £100 penalty follows automatically. Every year people penalise themselves this way when a penalty-free online route was still available.

If you are past 31 January as well, file as soon as you possibly can. The daily £10 penalties from the three-month point are the ones that hurt, and they only stop when the return goes in. If something genuinely prevented you from filing, such as serious illness or a bereavement, an appeal on reasonable excuse grounds may succeed, but get the return in first.

This is also where we should be upfront about our interest: filing SA109 returns for non-residents is a large part of what we do. Horizon UK Tax Solutions files through professional software with the SA109 included, so the 31 January deadline is preserved, and every return comes with the residence position checked properly: SRT day counts, the correct split-year case, treaty claims and, from 2025/26, whether a FIG regime claim makes sense given the loss of allowances. Our guide to split-year treatment covers the most common first-year scenario, and our fee estimator will give you a fixed quote in about a minute. If you are reading this in December with an unfiled return and a residence question, that is exactly the situation we deal with every January.