GST on first time buyer of Flat?

GST has to be paid over under-construction flat, but not over ready to move in flat having obtained CC. There is no rate difference for first time buyer or otherwise, but for affordable housing it is subsided to 8%, which normally is 12% over the cost of flat including land cost.

Yes, The GST rate has been reduced to 8% from 12% on purchase of houses availing of the credit-linked subsidy scheme (CLSS) under Pradhan Mantri Awas Yojna.

Under the scheme, a first-house buyer purchasing a house or apartment of up to 150 square metres (1,615 sq ft) carpet area with a household income of up to Rs 18 lakh per annum can avail a benefit of up to Rs 2.7 lakh.

Refer::  not-charge-gst-affordable-housing-buyers

And   cbec/gst/Consolidated_notification_CGST11