Debit balances are taken as zero for MAB calculation.
Monthly Average Balance = Sum of closing balance for all days in a month (Day 1 + Day 2 + Day 3 +...... + Day 30) Divided by Number of Days in a month (30).
Example: If the balances in Current Account are: October 1 (Rs 2000), October 2 (Rs 1000), October 3 (-Rs 1000, i.e., debit balance of Rs 1000), Average Balance as on October 3 = (Rs 2000 + Rs 1000 + Rs 0) / 3 = Rs 1000/-. Note: October 3 balance is taken as Rs 0 as it is in debit balance.