RDRM12010 advises Under the SRT, an individual is either UK resident or non-UK resident for a full tax year, and at all times in that tax year. However, if during a year the individual starts to live or work abroad, or comes from abroad to live or work in the UK, the tax year will be split into 2 parts, if their circumstances meet specific criteria: a UK part for which they will be charged to UK tax as a UK resident an overseas part for which, for most purposes, the individual will be charged to UK tax as a non-UK resident.
RDRM12010 - Residence: The SRT: What is a split year
This means that for the most part, foreign income in the non-UK resident period is not taxable in the UK. Some types of income are still taxable in the UK, such as income from property.
RDRM12160 goes on to advise, The overseas part of the tax year starts at the beginning of the tax year and ends the day before the earliest point at which an individual meets the only home test. The UK part of the tax year is the period from the end of the overseas part until the end of the tax year.
RDRM12160 - Residence: The SRT: Split year treatment: Case 4: The overseas and UK parts of the tax year