Hi
1) As per Para 5 of schedule III of the CGST Act, 2017, any payment made by the buyer to the builder on or after 1st July, 2017 against invoices issued on or after 1st July, 2017 shall attract GST @ 12% for an under construction property.
2) Unfortunately, the developer seems to be ignorant of GST rules( which is very common given the prevailing GST Confusion) or alternatively the developer might be banking on a loop hole in GST which says GST not applicable on second sale of apartments(i.e developer must have already sold the under construction property to some one else and in turn that person will be making a resale to you).
3) From your query, we understand that your developer has neither completed the flat nor is in possession of occupancy certificate issued by authorities. So, technically for any payment made by you to your developer on or after 01 July 2017, the same shall be subjected to 12% GST with Full Input Tax Credit available to you
4) Before making payment ask your developer the following:
a) Whether the developer is entering in to 2 sets of agreements with you i.e 1 agreement for sale of land along with undivided share of land and another agreement for construction. If so you need to pay GST at the rate of 12% with full input tax credit only for construction agreement.
b) Whether the developer will enter in to a construction agreement with you with an all inclusive rate per square feet and also mention specifically the stage wise payment required to be made you ?
c) If the developer will accept at least 70% of payments from you through your bank and issue receipt thereof.
If the Developer answers all of the a, b and c queries in affirmative, you can go ahead with the purchase.
Hope this information is useful.