Section 3(2)(b) in The West Bengal Additional Tax and One-Time Tax on Motor Vehicles Act, 1989
(b)An omnibus registered as a private service vehicle in any State, other than West Bengal, and plying in West Bengal under a temporary permit on any special occasion, seasonal business or particular temporary need, shall be liable to pay additional tax at the rate specified under the heading "A. Motor vehicles for carrying passengers not plying for hire:" in Schedule I.