This adjustment to the corridor reflects the fact that there will be a significant increase in the balances held in Exchange Settlement accounts due to the combined effect of the Bank's enhanced liquidity operations, bond purchases and term funding program. Maintaining a zero interest rate on these balances would increase the costs to the banking system. In the current environment, this would be unhelpful.
The increase in settlement balances is also expected to change the way that the cash market operates. In other countries, where there have been large increases in balances at the central bank, the cash rate equivalent has drifted below the target and transaction volumes in the cash market have declined. It is likely that we will see the same outcome in Australia.