An inquiry into allegations of influence peddling revolving around former president Jacob Zuma and businessman friends of his will begin formal public hearings in August and could take two years or more, the head of the commission said on Thursday.
The allegations around Zuma, forced from office in February by his ruling African National Congress (ANC) party, and the wealthy Gupta family have tarred major companies, among them, KPMG and McKinsey, and triggered the revolt against Zuma.
Zuma and the Guptas, who are Indian nationals, have consistently denied wrongdoing.
KPMG sacked its South African leadership in September last year after it found work done for companies owned by the Gupta family, "fell considerably short" of its standards.
Deputy Chief Justice Raymond Zondo, who is the head of the inquiry, said in a televised news briefing that the inquiry would likely take 18 months to two years "based on what we know now."
"It may well be that when the investigations go on we find that actually there needs to be more time than that," he said.
The commission stems from a 2016 anti-graft report by the Public Protector, a regulatory office with a robust constitutional mandate, that called for an investigation into what is known in South Africa as "state capture."
The commission will be able to make recommendations for prosecutions.