Gains in Year of Arrival or Departure
If you leave the UK during a tax year and cease to be resident or ordinarily resident in the UK, you may, by concession, not be liable for CGT on gains incurred from disposals made after the date of your departure.
If you become resident in the UK during a tax year, having been neither resident nor ordinarily resident in the UK at any time during the 5 tax years immediately preceding that year, you are, by concession, liable to CGT on gains tax only on gains arising from disposals made after the date of your arrival.
There is normally no charge to CGT on your assets when you leave the UK if you do not actually dispose of them, nor is there any revaluation of assets when you come to the UK.
However, in some cases, gains on which a charge has been held over or deferred, or which have been subject to a claim to reinvestment relief, may be brought back into charge if you become neither resident nor ordinarily resident in the UK. This charge will only apply to taxpayers leaving permanently or not returning within 3 years.