Capital gain related query

dear sir

let me present situation

Mr. X owns a land and he entered into development agreement with some contruction company to construction apparments in place by demolishing old structure. in return he gets 50% flat from developer.

now the question is whether the 50% flat is recd is taxable in capital gains or business income?

and when it is actually taxed? i mean whether in the year of completion of contruction or sale of flat by owner?