Hi,
In case of JDA, following are the implications under the GST law.
1) Tax on supply of development rights.
2) There are no specific rules of valuation of cost for residential real estate projects. It depends on the location and other aspects.
3) From 01.04.2019, GST rate reduced on real estate projects where there is a supply of flat or apartment. In yoir case, developer is providing construction service which attracts 18%.
Thanks