(Chapter: II Part F. - National Committee for Promotion of Social and Economic Welfare)
(2) The term of office of a member shall be for three years commencing on the date of notification.
(3) One of the members of the National Committee shall be appointed as Chairman by the Central Government. In the event of vacancy of the office of Chairman for any reason and until a new Chairman is appointed, no meeting of the National Committee shall be held :
Provided that if for any meeting, the Chairman is absent, the members present for the meeting may elect one amongst themselves to preside over the day's sitting.
(4) The National Committee may appoint one or more sub-committees from among its members for looking into specific areas of activity from time to time. The National Committee may invite any expert to examine any matter of technical nature.
Reference/Source: Check at Income Tax site for latest version of the Rules - link