Basic Customs Duty is not subsumed under GST. It is a separate tax on imported goods, aimed at regulating imports and supporting local businesses. Taxes on petroleum products, such as petrol and diesel, are also not included under GST. Central Excise Duties and Service Tax have been subsumed under GST, while taxes on petroleum products are not fully subsumed, but the question specifically asks for a tax that is not subsumed, making Customs Duties the correct answer.