If the construction of apartments are completed / occupancy certificate for the apartments is already obtained. There will not be any GST. Else it will we 1% for affordable houses or 5% for other than affordable Houses (If the construction was started after 1/05/2018 Further if it is old projects who has not opted for new rate it ll be 18% ( with 1/3rd land deduction) so effective rate would be 12%