UK non resident status

If you leave the UK to work full-time abroad under a contract of employment, you are treated as non resident and not ordinarily resident if you meet all the following conditions:

Your absence from the UK and your employment abroad both last for at least a whole tax year.

During your absence any visits you make to the UK total less than 183 days in any tax year, and average less than 91 days a tax year.  (The average is taken over the period of absence up to a maximum of four years.  Any days spent in the UK because of exceptional circumstances beyond your control, for example the illness of yourself or a member of your immediate family, are not normally counted for this purpose).