Important:
This answer is based on tax law for the tax year ending 28 February 2017.
Answer:
We don’t agree with your view regarding the resident status of the individuals concerned. You must determine that by applying Article 4, particularly paragraph 2 of the Agreement between the two countries - the date of entry into force is 1 December 2016.
In terms of Article 14(1), which we accept applies in this instance, “salaries, wages and other similar remuneration derived by a resident of a Contracting State (Zimbabwe) in respect of an employment shall be taxable … in … the State the employment is exercised in…”
If the persons are in fact residents of the RSA they must register for tax in the RSA and if they have RSA sourced employment income they may have to file a return of income and will have to register as well – the employer may have done the registration on their behalf.