QAB stands for Quarterly Average Balance, which is the average of all the closing day balances for any quarter. It is a requirement for certain savings accounts, and the account holder must maintain an average balance on a quarterly basis. The QAB is calculated by adding the closing day balances and dividing the sum by the number of days in the quarter. For example, if the QAB of an account is Rs. 10,000, it means that on average, the account holder needs to maintain Rs. 10,000 daily, but not necessarily every single day. The bank computes the average balance on a quarterly basis, i.e., once every three months. If an account holder fails to maintain the QAB, the bank may charge a penalty or non-maintenance fee. The minimum QAB varies across banks and locations, and banks keep changing the limits, so it is important to know the QAB from the bank.