What is split year treatment on a Self Assessment return?

Split year treatment lets someone who moves to or from the UK during a tax year be treated as UK resident for only part of that year under the Statutory Residence Test, rather than for the whole year, so overseas income before arrival or after departure is generally kept outside UK tax.

Split year treatment only applies if you are UK resident for the tax year overall under the Statutory Residence Test, and you then meet one of eight specific cases, such as starting full-time work overseas, your partner joining you abroad, or starting to have a home only in the UK partway through the year.

It is not a choice you elect for freely; you either meet the conditions for one of the cases or you do not, and each case has its own detailed tests around days, homes and work patterns that need checking against the actual facts.

Split year treatment is claimed on the SA109 residence, remittance basis etc. pages of the Self Assessment return, identifying the split year case and the date the overseas part begins or ends.

Getting it wrong, either by claiming it without meeting the conditions or missing a case that would apply, can materially change the tax due on income or gains realised around the date of the move, so the analysis is worth doing carefully rather than assuming the obvious date applies.

Rates, thresholds and deadlines quoted here reflect the 2026/27 UK position and current Companies House and HMRC guidance. Check GOV.UK, or ask us, before relying on them for your own company.