If a person is a gazetted officer, then he is a deputy secretary, a position which is not a gazetted officer.
The deputy secretary is a person who is appointed by the secretary of the ministry concerned to assist the secretary in the discharge of his functions.
In the case of the ministry of finance, the deputy secretary is the finance secretary.
The deputy secretary is not a member of the ministry, and his appointment is not subject to the approval of the ministry of finance.