1. if the builder has obtained Occupation Certificate or Completion Certificate from the Municipal or local body for the project in which you are buying the property, then there is no need to pay GST
2. GST is applicable only for under-construction flats as there is an element of service and also sale of goods involved before the construction is completed
3. Collecting GST from flat buyers and depositing the same with government is the liability of builder
4. If the builder has not obtained OC or CC or if such a certificate is not issued by the local body then you can request the builder to specifically mention in the sale agreement that the flat is completed in all respects and is being sold to you as such