Section 14(4)(b) in Central Civil Services (Classification, Control & Appeal) Rules, 1965
(b)On receipt of the articles of charge, the Government servant shall be required to submit his written statement of defence, if he so desires, and also state whether he desires to be heard in person, within a period of fifteen days, which may be further extended for a period not exceeding fifteen days at a time for reasons to be recorded in writing by the Disciplinary Authority or any other Authority authorised by the Disciplinary Authority on his behalf: