UK Split Year Treatment
A Complete Guide for Departing and Arriving Residents
The UK tax year runs from 6 April to 5 April the following year. Under the Statutory Residence Test (SRT), tax residence is normally determined on a full-year basis. This means if you are classed as a resident for even one day, you are technically treated as resident for the entire tax year and liable to UK tax on your worldwide income for that full period.
Split Year Treatment is a statutory exception to this rule. It allows a tax year to be divided into a UK-resident part (during which worldwide income is taxable in the UK) and an overseas part (during which only UK-sourced income is taxable). For anyone leaving or arriving in the UK mid-year, Split Year Treatment can make a massive difference to their tax liability.
Section 1: The Eight Cases
The Split Year rules are divided into eight mutually exclusive Cases. The first three apply to individuals leaving the UK, and the remaining five apply to those arriving.
Cases for Leavers (Departing UK)
You leave the UK to work full-time abroad (averaging at least 35 hours per week). The overseas part begins on the day you start your overseas work, subject to strict pro-rated limits on UK return days and work days.
You leave the UK to join a partner who is starting full-time work abroad. You must cease to have a UK home (or your presence there must fall below defined limits). The overseas part begins on the date of departure.
You had a home in the UK, but cease to have any home in the UK for the rest of the tax year. From that point, your UK visits must be strictly limited (below a pro-rated equivalent of 16 days). The overseas part begins on the day you cease to have a UK home.
Cases for Arrivers (Entering UK)
You did not have a UK home at the start of the year, but acquire one and cease to have any homes outside the UK. The UK part begins on the day you acquire the home.
You begin working full-time in the UK during the tax year. You must not have been resident in the prior three tax years. The UK part begins when the work period starts.
You cease working full-time overseas, return to the UK, and establish a UK home. The UK part begins on the day after the overseas work ends.
Your partner starts full-time UK work and you move to the UK to join them. The UK part begins when you arrive, provided you were non-resident in the prior three years.
Covers arrivers who start to have a UK home where Cases 4–7 do not apply, provided they were non-resident in the previous three tax years. The UK part begins when the UK home is established.
Section 2: Why Split Year Treatment is Not Automatic
Many taxpayers and even some professional advisers assume that if you leave the UK mid-year, you are automatically treated as non-resident from your move date onwards. This is incorrect.
Split Year Treatment is a claim-based mechanism. It must be actively claimed on the SA109 supplementary pages of your UK Self Assessment tax return, submitted by 31 January following the end of the relevant tax year (for online returns). If you do not claim it by this deadline, HMRC will treat you as resident for the entire tax year.
Furthermore, you must qualify under the strict statutory wording of one of the eight Cases. The Cases are not interchangeable. Each Case has detailed entry conditions that must all be satisfied simultaneously. Failing even a single condition in the applicable Case invalidates the Split Year claim, exposing your worldwide income to UK tax for the entire 12-month period.
Section 3: The Day Count Problem — Pro-Rated Thresholds
Qualifying for Split Year Treatment under Cases 1, 2, 3, and 6 depends on meeting specific day count conditions — both before and after the split date.
Importantly, these thresholds are pro-rated based on the number of days remaining in the tax year after your split date:
- Case 1 (Full-Time Work Abroad): Requires that from your departure date, you spend fewer than 91 days in the UK and no more than 30 days working in the UK. Because these limits are pro-rated, leaving late in the tax year gives you a significantly reduced allowable day limit.
- Case 3 (Ceasing a UK Home): Requires that after ceasing to have a UK home, you spend fewer than 16 days in the UK for the rest of the tax year. This 16-day limit is pro-rated based on the length of the overseas part of the year. For example, if you cease having a UK home halfway through the tax year, your post-departure day limit is reduced to 8 days.
- Case 5 (Full-Time Work UK): Requires calculating a specific number of working days in the UK over a defined pro-rated period.
Because these conditions apply starting from the specific split event date, you cannot rely on simple annual calculations. You must track your location day-by-day starting from the exact date you left or arrived.
Contemporaneous Evidence for HMRC
In a residency investigation, HMRC will require contemporaneous, third-party verifiable evidence of your location from the split date onwards. A GPS-backed, timestamped location log is the most robust way to defend your split year claim against HMRC inquiry.
Section 4: Common Mistakes
Assuming It's Automatic
You must actively claim Split Year Treatment on Section 3 of your SA109 tax return. There is no default split year assignment.
Incorrect Split Dates
The split date is defined by the matching Case, which does not always align with your physical travel date (e.g., in Case 1 it is when work begins).
Post-Split Day Violations
Forgetting that the day count limits in Cases 1 and 3 are pro-rated and apply strictly starting from your split date, not the start of the year.
Confusing Split Year and Domicile
Split Year only affects income tax. It does not shorten the 10-year inheritance tax tail for long-term former residents following the non-dom abolition.
Section 5: Interaction with the Non-Dom Abolition
For individuals leaving the UK following the April 2025 non-dom abolition, Split Year Treatment is the first tool available to limit UK tax exposure in the departure year.
Case 3 (ceasing to have a UK home) and Case 1 (starting full-time work abroad) are the most commonly claimed cases for departing non-doms.
It is critical to note that Split Year Treatment and the new Foreign Income and Gains (FIG) regime are separate:
- Split Year Treatment determines how the departure year is divided for UK tax.
- The FIG Regime determines whether foreign income and gains are exempt in subsequent years of non-residency.
For a detailed guide on managing your exit day count, see our dedicated article: UK Non-Dom Exit Day Count Tracking.
