Thanks for your response
Then he is at this time not treated as resident in the UK at all, but will be treated as resident in Singapore, where he actually lives and works.
So there will be no tax liability in the UK, unless, this position changes, and it would be prudent to review the situation as to his plans after June 2014, which may also affect the position right back to June 2013.
So without knowing what his plans are after June 2014 (or at least his intentions) then I cannot clarify whether he can be treated as not resident and therefore not liable to UK tax.
But I will also advise that IF the position (after June 2014) sees your brother having been treated as resident from the time he arrived in the UK then he cannot claim Non Dom. He can only claim Non Dom is NONE of the income comes into the UK.
So to recap
1) His arrival in the UK 2 weeks prior to this oversees employment saw him as being resident from the day he arrived
2) His taking up this employment abroad would initially see him treated as not resident, but to treated as not resident (so that he is not liable to UK tax) his employment contract abroad has to last more than a full tax year (so beyond 05/04/2015) However, this is on the assumption that he will return to live in the UK, after this employment ends. At this time his contract only lasts until June 2014, so were he to return to the UK at that time, he would be treated as UK resident throughout the period from June 2013 to June 2014, and liable to tax on this income from abroad (if any has been remitted to the UK
3) But for the time being, he will be liable to any form of taxation that exists in Singapore, as he is within their tax jurisdiction. And you will have to seek advise in Singapore or tax advise (as we do not offer other countries tax advise for Singapore on any of the Just Answer forums)