JDA related - all taxes

Base Info: Landowners: 3 brothers, 2 are Indian citizen one is foreign citizen Land in Metro city: 10000 SFT, inherited by all brothers from parents who expired 20 years ago Land original Purchasse price: Unknown, but very low. JDA Agreement likely to be signed in June 2021 Total estimated value of land @ Rs 20 Lacs per 1000 sft = 2 Crores (20 lacs x 10000 sft) Total Estimated saleable buit up area = 30000 sft (10000 x floor index of 3.00) Total estimated super builtup rate @ Rs 5000 / SFT = 15.00 Cr (Rs 5000 x 30,000 sft) Total estimated construction cost: @ Rs 2000/ SFT = 6.00 Cr (Rs 2000 x 30,000 sft) JDA Share: Builder 60%, 40% landowner JDA REFUNDABLE Advance on siging of agreement for each brother = 20 Lacs (Rs 60 Lacs total for 3 brothers) JDA Completion certificate expected by: June 2024 Land owner A: Indian Citizen wants revenue sharing in rupees Land owner B: Foreign citizen wants 50:50 Builtup area (sft) and revenue sharing (Rs) Land owner C: Indian Citizen wants wants Builtup area sharing in SFT Queries: What is GST liability and its estimated due dates for EACH owner in Rs (Required: estimated amount and a rough calculation based on current tax rates) What is Capital Gains Tax Liability and estimated due dates for EACH owner in Rs (Required: estimated amount and a rough calculation based on current tax rates) What is TDS liability and its estimated due dates for EACH owner in Rs (Required: estimated amount and a rough calculation based on current tax rates) (assuming all saleable units are sold in next one year). What is Stamp duty and its estimated due dates for EACH owner as applicable according to their sharing plans described above) Is it possble to save on capital gains tax if the gain is reinvested back in the purchase of more flats within same project?