Form SA109 is the supplementary schedule to the UK Self Assessment return used to establish your residence status, domicile, and whether you are taxed on the arising basis or the remittance basis under Finance Act 2013 (FA 2013, Schedule 45) and the Income Tax Act 2007 (ITA 2007).
Unlike ordinary supplementary pages, HMRC does not permit filing Form SA109 through its own free web filing portal; it must be filed through HMRC-recognised commercial software like ac-co or on paper.
The Statutory Residence Test (SRT)
Your UK tax residency is established under the statutory rules of Schedule 45 FA 2013 through a three-stage hierarchical test:
1. Automatic Overseas Tests
If you meet any of these tests, you are automatically non-UK resident for the tax year:
- You spend fewer than 16 days in the UK during the tax year (fewer than 46 days if you were not resident in any of the previous 3 tax years).
- You work full-time overseas (at least 35 hours per week) and spend fewer than 91 days in the UK, with no more than 30 UK workdays.
2. Automatic UK Tests
If you do not meet the overseas tests, you are automatically UK resident if:
- You spend 183 or more days in the UK in the tax year (a day is counted if you are in the UK at midnight).
- Your only home is in the UK for at least 91 consecutive days, and you spend at least 30 days there during the tax year.
- You work full-time in the UK for a 365-day period.
3. Sufficient Ties Test
If neither automatic test applies, residency depends on the combination of days spent in the UK and your UK connection ties (Family, Accommodation, Work, 90-day tie, and Country tie for leavers).
Split-Year Treatment (Schedule 45 Cases 1–8)
The UK tax year runs from 6 April to 5 April. While residency normally applies to the entire year, split-year treatment divides the year into:
- An overseas part: during which you are taxed as a non-resident (UK source income only).
- A UK part: during which you are taxed as a resident on worldwide income.
Split-year treatment applies automatically if you meet the statutory conditions of one of eight specific cases:
- Leaving the UK: Case 1 (starting full-time work overseas), Case 2 (partner of someone starting full-time work overseas), Case 3 (ceasing to have a home in the UK).
- Arriving in the UK: Case 4 (starting to have a home in the UK only), Case 5 (starting full-time work in the UK), Case 6 (ceasing full-time work overseas), Case 7 (partner of someone ceasing full-time work overseas), Case 8 (starting to have a home in the UK).
Remittance Basis vs Arising Basis
Non-domiciled individuals (non-doms) have historically been able to claim the remittance basis under Section 809B ITA 2007:
- Arising Basis: You pay UK tax on your worldwide income and gains as they arise.
- Remittance Basis: You pay UK tax on UK income/gains, but only pay UK tax on foreign income/gains if they are remitted to or enjoyed in the UK.
- Consequences: Claiming the remittance basis requires forfeiting both the Income Tax Personal Allowance and the Capital Gains Tax Annual Exempt Amount.
- Remittance Basis Charge (RBC): Long-term residents pay an annual charge (£30,000 for residence in 7 of the last 9 years; £60,000 for 12 of the last 14 years) to maintain the claim.