I have a piece of land that I purchased about 10 years ago. I entered an agreement with a real estate developer in 2014 for construction of apartments. The agreement was to give me 3 apartments in lieu of the land and keep the remaining 7 for him. The apartments will be handed over to me soon. When will the tax liability arise for payment of capital gains tax? Would it be when I get the apartments or when I sell them?

Thanks,