You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Nonprofit_organization

Context:
In South Africa, charities issue a tax certificate when requested by donors which can be used as a tax deduction by the donor. Non Profit Organisations are registered under Companies and Intellectual Property Commission as Nonprofit Companies (NPCs) but may voluntarily register with The Nonprofit Companies Directorate. Trusts are registered by the Master of the High Court. Section 21 Companies are registered under the Company's Act. All are classified as Voluntary Organisations and all must be registered with the South Africa Revenue Services "SARS".[citation needed]

Question:
Who would a South Africian NPO register with if they were a voluntary organization?

South Africa Revenue Services "SARS"