Section 26(2) in The West Bengal Premises Tenancy Act, 1997
(2)Where before the commencement of this Act, the tenant has, with or without the consent of the landlord, sublet any premises either in whole or in part, the tenant and every sub-tenant to whom the premises has been sublet, shall give notice to the landlord of such subletting in the prescribed manner [within two years of the commencement of this Act] [Words substituted for the words 'within six months of the commencement of this Act' by W.B. Act 14 of 2002.] and shall, in the prescribed manner, notify the termination of such sub-tenancy within one month of such termination.