Special audit:
Sec.66 (1) If at any stage of scrutiny, inquiry, investigation or any other proceedings before him, any officer not below the rank of Assistant Commissioner, having regard to the nature and complexity of the case and the interest of revenue, is of the opinion that the value has not been correctly declared or the credit availed is not within the normal limits, he may, with the prior approval of the Commissioner, direct such registered person by a communication in writing to get his records including books of accounts examined and audited by a chartered accountant or a cost accountant as may be nominated by the Commissioner.