State tax rate on specified building materials set for intra State supplies under GST, with notified tariff classifications and effective date. Notification prescribes a state tax rate of 6 per cent on intra State supplies of specified construction materials-fly ash bricks, fly ash aggregates, fly ash blocks, bricks of fossil meals or similar siliceous earths, building bricks, and earthen or roofing tiles-referencing the corresponding tariff items of the First Schedule to the Customs Tariff Act, 1975 for classification; interpretative rules of that Schedule and definitions from the West Bengal GST Act and Integrated GST Act apply, and the notification takes effect from 22nd September, 2025.