Understanding the Split Year Basis When Leaving or Returning to the UK

If you are leaving the UK, moving abroad for work, or returning after time overseas, Split Year Treatment could significantly affect how much UK tax you pay.

Many people assume UK tax stops the moment they leave — but that isn’t always true. The split year basis determines when UK tax applies and when it doesn’t, and getting it wrong can result in overpaying tax or HMRC penalties.

This guide explains:

• What the split year basis is
• When it applies
• How UK residency is determined
• What steps to take when leaving the UK
• Practical examples to make it clear

What Is the Split Year Basis?

The UK tax year runs from 6 April to 5 April the following year.

Split year treatment allows that tax year to be divided into two parts:

• UK part – when you are treated as UK resident
• Overseas part – when you are treated as non-UK resident

During the UK part, you are generally taxed on worldwide income.
During the overseas part, you are usually taxed only on UK-source income.

This can make a substantial difference to your tax bill.

Is Split Year Treatment Optional?

No.

Split year treatment:

• Applies automatically if HMRC conditions are met
• Cannot be claimed or opted out of
• Must be reported correctly on your Self-Assessment tax return

If you are non-UK resident for the entire tax year, split year treatment cannot apply.

To qualify, you must be UK resident for part of the tax year under HMRC’s residency rules.

How HMRC Determines UK Tax Residency

HMRC uses the Statutory Residence Test (SRT) to decide whether you are UK resident for tax purposes.

Automatic UK Residence Tests

You are automatically UK resident if any of the following apply:

• You spend 183 days or more in the UK during the tax year
• You have one home, and it is in the UK, where you stay at least 30 days
• You work full-time in the UK over a 365-day period, part of which falls in the tax year

If none of these apply, HMRC looks at your UK ties.

The Sufficient Ties Test Explained

If you’ve been UK resident in one or more of the previous three tax years, HMRC considers five UK ties:

1. Family tie – spouse, civil partner, or minor children in the UK
2. Accommodation tie – a UK property available for at least 91 days
3. Work tie – 40 or more UK workdays
4. 90-day tie – spent more than 90 days in the UK in either of the last two tax years
5. Country tie – the UK is where you spend the most time

Your residency depends on how many ties you have and how many days you spend in the UK.

UK Days vs Residency (Previously UK Resident)

When Split Year Treatment Applies

Split year treatment applies when all of the following are true:

• You were UK resident in the previous tax year
• You are UK resident for part of the current tax year
• You are non-UK resident in the following tax year
• You leave or return to the UK for a qualifying reason

HMRC recognises three qualifying situations.

Qualifying Situations for Split Year Treatment

1. Starting Full-Time Work Overseas

Split year treatment applies if you:

• Begin full-time work abroad
• Spend fewer than 91 days in the UK after leaving
• Work no more than 30 UK workdays

The overseas part starts from the date overseas work begins.

2. Joining a Partner Working Overseas

This applies if:

• Your partner qualifies as working full-time overseas
• You live together overseas
• You spend minimal time in the UK
• You have no UK home, or spend most of your time abroad

The overseas part starts when:

• Your partner starts overseas work, or
• You join them abroad

3. Ceasing to Have a UK Home

Split year treatment may apply if:

• You give up your UK home
• Spend fewer than 16 days in the UK
• Establish a permanent overseas home

If more than one situation applies, HMRC applies them in priority order:

1. Overseas work
2. Joining a partner
3. Ceasing UK home

What To Do When Leaving the UK

Step 1: Submit Form P85

This tells HMRC you’ve left the UK and helps process any PAYE tax refund.

Step 2: Review Your Residency Status

Your residency affects how your income is taxed — mistakes here are costly.

Step 3: Update Your Overseas Address

Ensure HMRC correspondence reaches you.

Split Year Treatment Example: Leaving the UK

Sarah leaves the UK on 31 October 2023 to work full-time in Dubai.

• UK resident in 2022/23 and 2023/24
• Non-UK resident in 2024/25
• Only 14 UK days after departure

Result for 2023/24:

• UK part: 6 April 2023 – 31 October 2023
• Overseas part: 1 November 2023 – 5 April 2024

Sarah pays UK tax only on UK income during the overseas part.

Example: Returning to the UK

Sarah returns to the UK on 1 December 2025 and resumes full-time UK work.

Result for 2025/26:

• Overseas part: 6 April 2025 – 30 November 2025
• UK part: 1 December 2025 – 5 April 2026

Worldwide income becomes taxable again from the return date.

How Split Year Treatment Is Reported

Split year treatment is reported on:

• SA100 – Self-Assessment tax return
• SA109 – Residence pages

SA109 cannot be filed directly on HMRC’s website — it requires approved software or professional submission.

This is one of the most common areas where HMRC challenges returns.

Why Professional Advice Matters

Split year treatment is high-risk and frequently reviewed by HMRC. Errors can result in:

• Overpayment of UK tax
• Delayed refunds
• Incorrect residency status
• HMRC enquiries and penalties

A properly prepared return ensures:

• Correct residency analysis
• Accurate SA109 completion
• Tax efficiency and compliance

Need Help With a Split Year Tax Return?

If you are:

• Leaving the UK
• Returning after working abroad
• Unsure of your residency status
• Required to complete SA109

Our UK-based accountants specialise in Self-Assessment, non-resident tax, and split year treatment.

Get your tax return done correctly — first time

FAQs: Split Year Basis UK

Is split year treatment automatic?
Yes, if conditions are met — but it must be reported correctly.

Can HMRC reject split year treatment?
Yes, if residency or day counts are incorrect.

Do I still need to file a tax return?
Yes, if you meet Self-Assessment criteria.

Can I file SA109 myself?
Not through HMRC’s online system — specialist software is required.