Section 4 in The Comptroller And Auditor-General's (Duties, Powers And Conditions Of Service), Act, 1971
4. Term of office
The Comptroller and Auditor-General shall hold office for a term of six years from the date on which he assumes such office:Provided that where he attains the age of sixty-five years before the expiry of the said term of six years, he shall vacate such office on the date on which he attains the said age :Provided further that he may, at any lime, by writing under his hand addressed to the President, resign his office.Explanation.— For the purpose of this section, the term of six years in respect of the Comptroller and Auditor-General holding office immediately before the commencement of this Act, shall be computed from the date on which he had assumed office.
