Timing of GST liability on development-rights exchanges arises on transfer of possession by conveyance or similar instrument. The notification designates registered persons exchanging development rights and construction services and fixes the timing of tax liability for state tax: liability arises when the developer or other registered person transfers possession or the right in the constructed complex to the supplier of development rights by entering into a conveyance deed or similar instrument, treating consideration in the form of construction service or development rights as taxable.