Hi Detail Rec,
If an individual moves overseas on a long term basis and becomes tax resident in the overseas country, but continues to work remotely for a UK employer, it is likely that the other country will tax his employment income.
Employees who spend most of their time abroad over a period of a year or more may be able to obtain full UK tax relief on their earnings by completing form P85 and sending it to HMRC who will confirm the tax code to use
For more information on what is expected of employers and employees in this kind of situation, please refer to the following guidance:
Employees working abroad