Section 115(7) in The Central Motor Vehicles Rules, 1989
(7)[ After the expiry of a period of one year from the date on which the motor vehicle was first registered, every such vehicle shall carry a valid"Pollution under control" certificate issued by an agency authorized for this Purpose by the State Government. The validity of the certificate shall be for [six months] [Added by GSR 338(E), dated 26.3.1993 (w.e.f. 26.3.1993). ] and the certificate shall always be carried in the vehicle and produced on demand by the officers referred to in sub-rule (1) of rule 116.[Provided that the validity of the certificate shall be twelve months for the vehicles manufactured as per [Bharat Stage-IV or Bharat Stage-VI] [Inserted by Notification No. G.S.R. 103 (E) dated 23.2.2012 (w.e.f. 2.6.1989)] norms.]