CGT When You Leave the UK — What Happens to Your Shares?

Relocating abroad is exciting. The tax implications are less so. Moving doesn’t automatically free you from UK CGT — and there’s a specific trap that catches people who leave temporarily and come back.

The general principle

If you’re UK tax resident, you pay CGT on worldwide gains. Sell shares on any exchange, in any currency, anywhere — it’s taxable in the UK. Your residence status is determined by the Statutory Residence Test (SRT), which considers days in the UK, ties, and work patterns.

If you become non-UK resident, you generally don’t pay UK CGT on share disposals (though UK property disposals are still caught — a separate set of rules applies).

The temporary non-residence trap

Under TCGA 1992 s.10A, if you leave the UK, sell assets while non-resident, and return within 5 complete tax years, the gains are treated as arising in the year you come back. You pay UK CGT on them as if you’d never left.

The rule applies if you were UK resident for at least 4 of the 7 tax years before departure. Most long-term UK residents meet this criterion.

Example: You leave the UK in July 2025, sell £100,000 of shares in 2026, and return in 2029. Those gains are taxed in your 2029/30 UK return — you don’t escape CGT at all.

The HMRC guidance on residence, domicile and remittance covers the interaction of these rules in detail. The Experts for Expats guide to UK CGT for non-residents is also a practical resource.

Planning before you leave

If you’re genuinely emigrating (not coming back within 5 years), you have an opportunity to crystallise gains while still UK resident and use your annual exemption.

Sell enough to use your £3,000 exemption in your final UK tax year. Consider doing a bed and ISA — ISA gains remain permanently tax-free regardless of residence.

If you’ll be resident in a country with no or low CGT (like Portugal’s NHR regime, or many Middle Eastern countries), it may be worth deferring sales until after departure — but only if you’re confident you won’t return within the 5-year window.

The 2025 non-dom changes

From April 2025, the UK replaced the domicile-based tax system with a new residence-based regime. New arrivals to the UK get a 4-year exemption on foreign income and gains. Long-term residents (10+ years out of the last 20) are now taxed on worldwide gains regardless of domicile.

If you’re arriving in the UK as a new resident, the 4-year FIG (Foreign Income and Gains) relief can shelter significant gains. If you’re leaving after a long stay, the temporary non-residence rules still apply as before.

Self-assessment in the year of departure

In the tax year you leave the UK, you may be a “split-year” case — UK resident for part of the year and non-resident for the rest. The SRT has specific split-year provisions. Capital gains during the UK-resident portion are taxable; those during the non-resident portion generally aren’t (subject to the temporary non-residence rules).

Calculate your position using TaxBull — it separates gains by date, so you can identify which disposals fall in the UK-resident period and which don’t. File your SA108 for the year of departure covering only the resident-period gains.

International tax is genuinely complex. This is an overview, not advice. Always consult a qualified cross-border tax adviser before making decisions based on residence status.