GST classification of iron and steel structures subjects such goods to the scheduled tax rate until a notified transitional deadline. Fabricated iron or steel structures and their component parts (for example bridges, towers, roofing frameworks, doors and windows with frames and thresholds, shutters, balustrades, pillars, columns) and prepared plates, rods, angles, shapes, sections and tubes for use in structures are classified under the tax schedule; prefabricated buildings are excluded, and these goods attract GST @ 18% until the notified transitional deadline.