Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
First things first; when you left the UK in 2010 did you submit a Form P85 to the UK tax authorities? If you did not you should do so immediately. Fortunately there is no time limit as to its submission, it is available on the web and can be filed on line. Once submitted HMRC will classify you as non resident. Once you are in the P85 procedure when you return to the UK you advise HMRC of your return. You will then be subject to the split year treatment, one portion non resident and the other resident. Thus you will not be liable for overseas earnings received during your non resident portion.
Once you are in the non resident status you may return to the UK for not more that 91 days in any one tax year whilst retaining non resident status. Unfortunately your move to Qatar in 2016 and the return is too short a period for P85 action. You will have been over 183 days in the UK for both 15/16 and 16/17 tax years and thus be liable to UK taxation on your world wide income for those years.
I am so sorry to have to rain on your parade.
Your P85 action for January 2016 will be ineffective as you will not have been out of the UK over a complete tax year.
The government may not know how much you earned in the Middle East, but you must still declare it on your self assessment tax return. Failure so to do would be a criminal offence. Remember Lester Piggott went inside for similar shenanigans. Remember that exchange of tax information between countries is becoming increasingly common.
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Of you come back after the start of the 17/18 tax year [6 April] then the P85 will be effective and the split year principles apply for both the leaving and the returning tax years.
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