Margin-based state tax reduction on used motor vehicles applies with specified rates and exclusions under GST by notification. State tax on intra State supplies of specified old and used motor vehicles is exempted to the extent tax exceeds amounts calculated on the margin of the supplier, with reduced rates for listed vehicle categories. Margin is the difference between consideration and depreciated value for depreciated goods, or between selling and purchase price otherwise, and negative margins are ignored. The exemption is unavailable where the supplier has availed input tax credit, CENVAT, VAT credit or other taxes paid on the goods. The notification is effective from issuance.