What the SA109 covers
The SA109 is where your residence position is formally declared and where residence-based claims are made. GOV.UK describes it as the page used to record your residence and domicile status on the SA100 tax return and to claim personal allowances as a non-UK resident. In practice it carries your Statutory Residence Test outcome, any split-year claim when you leave or arrive part-way through a tax year, treaty residence claims if you are dual resident, and claims under the 4-year foreign income and gains (FIG) regime that replaced the remittance basis from 6 April 2025. Legacy remittance basis matters, such as pre-2025/26 foreign income now remitted to the UK, also go here. Our guide to split-year treatment covers the most common first-year scenario.
Who typically needs it
Broadly, anyone whose UK tax position turns on residence: people who have left the UK but keep UK income such as a rental property, new arrivals claiming split-year treatment or the FIG regime, non-residents claiming the personal allowance or double taxation relief, and dual residents relying on a treaty tie-breaker. For each year a return is due, the residence claims are made on that year's SA109.
How it is filed
The SA109 goes in with the rest of your return as a single submission, but HMRC's free online service does not support it, and GOV.UK states that non-residents cannot use HMRC's online services to report their income. That leaves three routes: post the whole return on paper, which HMRC must receive by 31 October (31 October 2026 for the 2025/26 year); file through commercial software that supports the SA109 by 31 January (31 January 2027); or use an agent, who files through professional software by the same January deadline. Posting a paper return after 31 October triggers an automatic penalty even though the online window is still open, so late starters should switch routes rather than post. If you want the paper route, download the SA109 form 2026 and its notes from the GOV.UK SA109 page; the notes say plainly that to submit these pages online you need commercial software or an agent, and that you must not attach them electronically to an online return. See why the SA109 cannot be filed online for the options in detail.