GST exemption for TDR and FSI proportionate to carpet-area; reverse-charge applies on unbooked residential units at project completion The amendment exempts integrated tax for transfer of development rights (TDR) or FSI and for upfront amounts for long term land leases when used for construction of residential apartments for sale, with the exempt amount calculated by the ratio of residential carpet area to total carpet area. Promoters must pay tax on reverse charge for proportions attributable to residential apartments un booked at completion or first occupation, subject to specified caps. Deemed value rules fix the value of TDR/FSI and un booked apartments by reference to similar apartments charged to independent buyers near the relevant dates.