The supplementary pages where you tell HMRC you were not resident, or were only resident for part of the year. Leave them out and the return you filed says, silently, that you were resident all year.
Most of the work of leaving the UK for tax purposes happens on one supplementary form. SA109 carries your residence status, your split-year claim and its case number, the days you spent here, your ties, and any claim about domicile or the remittance basis. It is short, dense, and the single place where a departure either gets recorded properly or does not get recorded at all.
The trap is structural rather than technical. HMRC's own free online Self Assessment service does not support the residence pages. Someone who has always filed their return on the HMRC website, and who does so again in the year they emigrate, will find no residence section, will file anyway, and will have submitted a return that treats them as UK resident for the entire year.
What You Are Actually Declaring
- Your residence status for the year, as a positive statement rather than an inference from the rest of the return.
- Split-year treatment, including which of the eight cases you rely on and the date the year splits. Our guide to the split-year cases covers how the case is chosen.
- Days and ties — the raw inputs to the Statutory Residence Test, which is why keeping a travel record from the day you decide to leave is not paranoia.
- Domicile and remittance, where relevant, along with claims connected to arriving in the UK.
- Personal allowance entitlement as a non-resident, where a treaty or nationality gives it.
Filing It: Three Real Options
- Commercial software. Third-party Self Assessment packages support SA109 and file the whole return electronically. This is what most people end up doing, and it is usually the cheapest of the three.
- Paper. Perfectly valid, but the paper deadline falls earlier in the year than the online one, which means a decision to go paper is effectively made in the autumn, not in January.
- An accountant. Sensible in the year of departure specifically, when the residence position, a split year and possibly an employment cessation all land in the same return.
The deadline difference is the thing that bites. People discover the online service will not take SA109 in January, conclude they will file on paper instead, and find the paper deadline has already gone. Decide which route you are taking early in the autumn, not at the last minute.
SA109 Is Not a Substitute for P85 — or the Reverse
These two forms do different jobs and the overlap confuses almost everyone. P85 is a PAYE-side notification that gets a refund moving after you stop being paid through a UK payroll. SA109 is part of your annual return and is what actually establishes your residence position for the year. Someone inside Self Assessment generally needs the return; someone leaving a job and not otherwise filing may need only the P85. People working abroad full time for a UK employer frequently need both.
Records the Form Assumes You Kept
| What SA109 asks for | What you need to have kept |
|---|---|
| Days spent in the UK | Boarding passes, passport stamps, a dated travel log |
| UK workdays | Diary entries showing where work was physically done |
| Accommodation ties | Tenancy end dates, sale completion, nights stayed with relatives |
| Split-year date | Contract start date abroad, or the date the UK home ended |
None of this is retrievable two years later from memory, and HMRC's questions when they come are specific. Our note on proving non-residence sets out what an evidence file should contain.
When You Can Stop Filing
Filing SA109 does not commit you to a UK return forever, but nor does leaving the country end the obligation by itself. Non-residents with UK rental income, or with a residence claim to make, usually keep filing. See when you can stop filing for how that ends properly rather than by silence.
Frequently Asked Questions
Why can I not file SA109 on the HMRC website?
HMRC's free online Self Assessment service has never supported the residence pages. You need commercial filing software, a paper return, or an agent. This is a known limitation rather than a fault with your account.
What happens if I file without SA109?
You have filed a return that presents you as UK resident for the whole year, with no split-year claim and no non-residence claim on record. It is fixable by amending the return, but until it is amended that is the position HMRC holds.
Do I need SA109 every year I live abroad?
Only for years in which you are required to file a return at all, and in those years the residence pages are how your non-resident status is stated. If your UK filing obligation ends, so does the need for SA109.
Is SA109 the same as claiming split-year treatment?
SA109 is the form on which the split-year claim is made, along with the case number and split date. The claim exists because you made it on the form, not because the facts are obvious.
Related Guides
Keep reading with these related guides and calculators:
- Split-year cases — the claim SA109 carries
- Form P85 — the other departure form, and what it does instead
- When to stop filing — ending the obligation properly
- Proving non-residence — the records the form assumes
- Payments on account — the other Self Assessment trap
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