law: Railways Act, 1989
  185. Taxation on railways for advertisement. 
  (1) Notwithstanding anything to the contrary contained in any
  
  other law, a railway administration shall not be liable to pay any tax to any
  
  local authority in respect of any advertisement made on any part of the railway
  
  unless the Central Government, by notification, declares the railway
  
  administration to be liable to pay the tax specified in such notification.
  (2) The Central Government may at any time revoke or very a
  
  notification issued under sub-section (1).