A DTA becomes relevant to your circumstances if you are earning an income for instance in South Africa as well as abroad, or if you are a tax resident of South Africa (but have no income from a South African source) and you are earning income from a foreign source.
This type of situation often gives rise to a grey area as to whether or not you can or should be taxed, especially taking into account that a South African tax resident would be subject to tax in South Africa on their worldwide income.
Thus, many South Africans living and working abroad may need to consider what their tax treatment legally should be when taking into account the DTA between South Africa and the country they are now residing in. There is the possibility that you may need to pay tax on your foreign income in South Africa and utilising a DTA is one of your options to ensure this does not happen.