Write a detailed note on Special Audit under Section 66 of the CGST Act, 2017.

Special Audit under Section 66 of the CGST Act, 2017: Section 66 of the CGST Act, 2017, provides for a 'Special Audit' in certain circumstances. This audit is distinct from the regular audit conducted by tax authorities or the annual audit by a Chartered Accountant/Cost Accountant. (i) Initiation of Special Audit: 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. (ii) Submission of Report: The chartered accountant or cost accountant so nominated shall, within the period of ninety days, submit a report of such audit duly signed and certified by him to the said Assistant Commissioner. (iii) Extension of Period: The Assistant Commissioner may, on an application made to him in this behalf by the registered person or the chartered accountant or a cost accountant on sufficient reason, extend the said period for another ninety days. (iv) Expenses of Audit: The expenses of an examination and audit, including the remuneration of such chartered accountant or a cost accountant, shall be determined and paid by the Commissioner. (v) Action based on Findings: On the findings of the special audit, the proper officer may take action under Section 73 (determination of tax not paid or short paid or erroneously refunded or input tax credit wrongly availed or utilized for reasons other than fraud or willful misstatement or suppression of facts) or Section 74 (determination of tax not paid or short paid or erroneously refunded or input tax credit wrongly availed or utilized by reason of fraud or willful misstatement or suppression of facts) of the CGST Act, 2017.