CG26305 - Arrival in and departure from UK: temporary non-residence: gains in year of arrival or return - years up to and including 2012-13
Where an individual arriving in the UK has not been resident or ordinarily resident in the United Kingdom at any time during the five years of assessment immediately preceding the year of assessment in which he or she arrived in the United Kingdom, the concessionary treatment is available under paragraph 1 of ESCD2. In such cases gains from disposals made in the year of arrival before the date of arrival are not chargeable to Capital Gains Tax.
Where the individual was previously resident in the UK and there are less than five tax years between the year of return and the earlier year of departure then the concessionary treatment does not apply. Gains from disposals made in the year of arrival both before and after the date of arrival are chargeable to Capital Gains Tax.
Note that the concessionary treatment under ESCD2 will always be available to a person who arrives in the UK to take up residence for the first time and who has not been resident for tax purposes previously.