Section 4(b) in The Central Secretariat Service Assistants' Grade (Direct Recruit Competitive Examination) Regulations, 2010
(b)He must belong to such categories of persons as may from time to time be notified in this behalf by the Government of India in the Department of Personnel and Training, Ministry of Personnel, Public Grievances and Pensions.(ii)Age - He must have attained the age of20 years, and must not have attained the age of27 years on the 1st day of August of the year in which the examination is held:
