My son (23 years old) graduated in 2017 and currently lives at home in the UK is starting a 'job' as a cameraman in Botswana in Sept 2018. He will be a self-employed contractor and invoice the Botswanan film company a monthly sum in GBP (although this may be paid in Botswanan currency). The contract is for a year (if all goes well), although he has the option to leave for up to a month if another film project (in the UK) materialises and is likely to return to the UK (for a week or two) at least once or twice during the year. He is currently unemployed and and has claimed universal credit for the last 3 months or so. He intends registering as self-employed in the UK and will submit self-assessment tax returns from January 2019 onwards. It is likely that his level of profit (particularly after deduction of travel costs) will be such that he pays little or no tax in the UK nor any student loan repayments (unless another project comes to fruition). Our understanding of the (highly complex) statutory residence tests is that he should be regarded as UK tax resident unless he ends up staying in Botswana for a complete tax year (eg to April 2020). Does this sound correct? Is there anything else he needs to do to ensure he is taxed in the UK rather than in Botswana (where the tax free allowances are lower)?
That's broadly right. your son would still be UK tax resident unless he spends a complete tax year outside of the UK. Also do keep in mind that simply being UK resident won't get him out of being taxed in Botswana as you would have to consider the tax residency position separately in Botswana. At a high level , if possible he should keep his days in Botswana to less than 183 days in any rolling 12 month period and spend the rest of his time in the UK. This should help to minimise the risk that he's actually considered treaty resident in Botswana but your son should also obtain tax advice in Botswana to ensure he's not triggering a tax liability.