What Should I Do About UK Tax and National Insurance Before Leaving the UK?

Posted on 5th February 2026 at 18:00

Leaving the UK to work, retire, or relocate abroad is a major life decision. But many people underestimate the tax and National Insurance consequences of moving overseas.

A common mistake is assuming UK tax responsibilities end the moment you leave. In reality, failing to plan properly can lead to unexpected tax bills, penalties, or long-term issues with pensions and benefits.

This guide sets out the key tax and National Insurance steps to take before leaving the UK, in the correct order.

1. How Do I Check Whether I Will Still Be UK Tax Resident After I Leave?

Your UK tax position is driven by your residence status, not simply where you live.

The UK uses the Statutory Residence Test (SRT), which considers:

How many days you spend in the UK

Whether you work in the UK

Whether you keep a home in the UK

Family and other ongoing ties

In the year you leave, Split Year Treatment (SYT) may apply. This can divide the tax year into:

A UK-resident part, and

A non-UK-resident part

This is often misunderstood and incorrectly applied.

Before leaving the UK, you should assess:

Whether you are likely to become non-UK resident

When your residence status actually changes (this is not always your departure date)

Whether Split Year Treatment is available

Getting this wrong can mean paying UK tax on overseas income unnecessarily.

2. How Do I Tell HMRC I Am Leaving the UK?

You should inform HM Revenue & Customs that you are leaving the UK.

This is usually done by submitting form P85, if you are leaving to live or work abroad and expect to become non-UK resident.

The P85 allows HMRC to:

Update your tax records

Consider whether you are due a tax refund

Apply Split Year Treatment (SRT) where appropriate

If you are employed, your employer should give you a P45 when you leave. This may need to be submitted with the P85.

If you complete a Self Assessment tax return, you should also:

Declare your departure date

Provide your overseas address

Confirm whether Split Year Treatment applies

3. What UK Income Will Still Be Taxable After I Move Abroad?

Leaving the UK does not necessarily mean leaving UK tax behind.

Many people continue to receive UK-source income, including:

Rental income from UK property

Certain UK pensions

UK dividends and interest

You may still be required to:

File a UK tax return

Pay UK tax on some or all of that income

You should also check whether the UK has a Double Taxation Agreement with your new country of residence. These treaties determine:

Which country has taxing rights

How double taxation is relieved

If you rent out UK property while living abroad, registering for the Non-Resident Landlord Scheme is essential.

What Counts as a Crown Employee for SDLT?

Why Timing Matters When Accessing a UK Pension

Many expats first discover NT tax codes after tax has already been deducted from their pension.

While it is often possible to reclaim overpaid tax, this can involve:

Complex paperwork

Long processing time

Uncertainty around exchange rates and final tax costs

Securing an NT tax code before taking pension income or large lump sums is almost always the cleaner and more efficient approach.

4. What Are the Capital Gains Tax Risks When Leaving the UK?

Capital Gains Tax (CGT) is one of the most commonly overlooked issues when leaving the UK.

Key points to consider:

UK property remains within the UK CGT net even after you become non-resident

The timing of asset disposals can significantly affect your tax bill

Selling assets shortly before leaving can sometimes result in higher tax than expected

You should also be aware of the temporary non-residence rules. If you leave the UK for fewer than five complete tax years and then return, certain gains realised while abroad can be taxed retrospectively.

Advance planning is essential if you expect to sell:

Property

Business interests

5. What Happens to My National Insurance When I Leave the UK?

National Insurance is often ignored, but it is critical for:

UK State Pension entitlement

Certain contributory benefits

When you leave the UK:

Your obligation to pay NIC may stop

Gaps in your record can reduce your State Pension

Before leaving, you should:

Check your National Insurance record

Review your State Pension forecast

Consider whether voluntary contributions may be appropriate

Failing to do this can result in a permanently reduced pension later in life.

6. What If I Am Working Abroad for the Same Employer?

If you are moving overseas but remaining with the same employer, special rules may apply.

Depending on the circumstances:

UK tax or NIC may continue for a limited period

Different payroll rules may apply for short-term assignments

It is essential that:

Your employer understands your departure date

Your overseas work location is correctly recorded

Payroll treatment is reviewed before you leave

Errors can be difficult and time-consuming to fix once you are abroad.

7. What Records Should I Keep Before Leaving the UK?

Good record-keeping is vital.

Before leaving, keep copies of:

P45s and P60s

Previous tax returns and HMRC correspondence

National Insurance contribution records

Evidence of departure (flight details, visas, contracts)

These documents are often crucial if HMRC later queries your residence status or tax position.

Final Thoughts: Why Planning Before You Leave the UK Matters

Tax and National Insurance issues are among the most important, and most complex, aspects of leaving the UK.

By addressing these points before you go, you can:

Avoid unexpected tax bills

Reduce the risk of HMRC disputes

Protect your long-term pension position

Move abroad with confidence

If you are planning to leave the UK and want clarity on your tax position, our specialist expat tax team can help.

📧 info@expat-tax-advice.co.uk

🌐 www.expat-tax-advice.co.uk

☎️ +44 1249 816810

Frequently Asked Questions

Do I stop paying UK tax as soon as I leave the UK?

No. Leaving the UK does not automatically end your UK tax obligations.

Your tax position depends on your UK tax residence status, which is determined under the Statutory Residence Test. Many people remain UK tax resident for part or all of the tax year in which they leave, particularly where Split Year Treatment applies.

You may also continue to pay UK tax on UK-source income after leaving.

How do I know when I become non-UK resident for tax purposes?

You become non-UK resident only when you meet the conditions of the Statutory Residence Test (SRT).

This depends on:

Days spent in the UK

Whether and where you work

Whether you keep a home in the UK

Family and other ongoing UK ties

Your residence status often changes after your physical departure date, not on the day you leave.

Do I need to tell HM Revenue & Customs that I am leaving the UK?

Yes.

If you are leaving the UK to live or work abroad and expect to become non-UK resident, you should notify HMRC, usually by submitting form P85.

If you complete Self Assessment, you must also declare:

Your departure date

Your overseas address

Whether Split Year Treatment (SRT) applies

Failing to notify HMRC can lead to incorrect tax assessments.

Will I still need to file a UK tax return after moving abroad?

Possibly.

You may still need to submit a UK tax return if you have:

Rental income from UK property

UK pension income

Other taxable UK-source income

Non-residents often continue to have UK filing obligations, even if they live abroad permanently.

Is UK rental income still taxable if I live overseas?

Yes.

UK rental income remains taxable in the UK even if you are non-resident.

If you rent out UK property while abroad, you should register for the Non-Resident Landlord Scheme. Without this, tax may be deducted at source by your letting agent or tenant.

Can I be taxed twice on the same income after leaving the UK?

Potentially, yes, but this is often relieved.

The UK has Double Taxation Agreements with many countries. These treaties determine:

Which country has taxing rights

How double taxation is relieved, usually through credits or exemptions

Treaty positions are technical and should be reviewed carefully before departure.

What happens to Capital Gains Tax when I leave the UK?

Capital Gains Tax does not disappear when you leave.

Key points:

UK property remains subject to UK CGT even after you become non-resident

Timing asset disposals incorrectly can significantly increase your tax bill

Temporary non-residence rules can apply if you return to the UK within five full tax years

CGT planning should be considered before leaving the UK.

Do I still pay National Insurance after leaving the UK?

It depends on where you move and whether you work.

In many cases, National Insurance contributions stop when you leave. However, gaps in your NIC record can reduce your UK State Pension entitlement.