The inquiry into administration and governance issues at SARS will hold it’s first public hearing on Tuesday.
President Cyril Ramaphosa announced the probe in May.
He is promising to take steps to stabilise Sars in order to meet revenue targets.
He appointed retired judge Robert Nugent to head the inquiry.
SARS has been rocked by various scandals, including alleged unauthorised bonuses to top executives.
This inquiry is separate from the disciplinary process instituted against SARS Commissioner Tom Moyane as well as the Davis Tax Committee, which is focusing on specific policy issues.