The cash reserves that commercial banks are legally required to keep are held in the form of at the South African Reserve Bank, where they earn no interest.

The cash reserves that commercial banks are legally required to keep at the South African Reserve Bank (SARB) are known as "required reserves" or "cash reserves." These reserves serve as a safety net and ensure that banks have enough liquidity to meet customer withdrawals and other obligations. Importantly, these reserves earn no interest, meaning that while they provide a secure holding for funds, they do not generate income for the commercial banks.

This requirement is part of the central bank’s monetary policy tools, aimed at controlling the money supply and maintaining financial stability within the banking system. By mandating that banks hold a certain percentage of deposits as reserves, the central bank can influence lending, credit availability, and overall economic activity. The concept of required reserves is a fundamental component of banking regulations in many countries, including South Africa.