Alcohol has a unique position under GST. Goods and services tax has been defined in the Constitution as a tax on supply of goods and services, so anything which forms a goods or services is taxed under GST. 

However the definition itself excludes alcoholic liquor for human consumption, which basically means that liquor can never be subjected to GST unless the Constitution itself is amended another time. 

The net outcome is that liquor is subject to State taxes, it is subject to State excise duty and it is also subject to State VAT, which situation will continue unless the Constitution is amended again.