Explanation:

The Chairperson, CBDT is the senior-most IRS civil servant in the Government of India. The Chairperson of Central Board of Direct Taxes is the ex officio Special Secretary to the Government of India and also cadre controlling authority of the Indian Revenue Service.
Senior Indian Revenue Service officer Sushil Chandra was on Wednesday appointed chairperson of the Central Board of Direct Taxes (CBDT), the apex policy making body for the income tax department. He will replace Rani Singh Nair, who retires this month-end.