Concessional GST on used vehicles applies tax only on the supplier's margin, subject to input tax credit exclusion. Concessional IGST applies to inter state supplies of specified old and used motor vehicles by taxing only the supplier's margin above a prescribed base rate. Vehicle categories are defined by tariff headings and physical specifications. Margin is computed as consideration less depreciated value if depreciation was claimed, or as selling price less purchase price otherwise, with negative margins ignored. The scheme does not apply if the supplier has availed input tax credit, CENVAT, VAT credit or other taxes on the goods.