Dear Sir,
Hope you are dong well !!
Land owner has to pay capital gain tax both the times.
1. At the time of receipt of completion certificate.
2. At the time of sale of that flat.
Capital gain will be taxable when the completion certificate will be issued and sale consideration will be stamp duty value/Market value of flats & Cost of acquisition will be share of flats in land or FMV of land if purchased by you before 2001.
At the time of sale of flats capital gain will be taxable again and that time sale consideration would be stamp duty value at that time and cost of acquisition would be stamp duty value considered today. You need to pay capital gain twice first against sale of land and second again sale of flats.
-In your case GST liability will arise on both events.
1) Sale of Rights in land by Land Owner to developer.
2) Construction Service provided by developer to Land Owner.
When you (Land Holder) will transfer rights in Land to developer, Gst will be levied on this transaction . Time of supply will be considered to be the date on which the said developer transfer the possession certificate or similar instrument to you( Land Owner).
Now, even developer has to pay GST on construction service provided by him to you.
If you need any further assistance, please call me. As a part of real estate industry, we will guide you in proper manner.
Thanks & Regards,
Payal Chhajed