Acceptance of demonitised currency

Is acceptance of demonitised currency against cash sales from 09/11/2016 liable to be treated as unexplained cash credit?. As payments to creditors are overdue and buyers were ready to pay in demonitised currency, my client accepted cash from various customers and deposited the same in the bank. Now client cannot identify the customers by address or PAN. What is the implication under tax laws or any other laws