In the case of immoveable property, Transfer of property act considers a sale as complete only on registration of the sale deed.
2)Under Transfer of property act, transfer of immoveable property is not complete unless the sale deed is registered. There may be situations where the buyer has acquired the possession of the property and the seller has been paid the price for the sale even though the property has still not been registered in the name of the purchaser
3)
For the purposes of Capital Gains, ‘Part performance of a contract of sale’ falls within the definition of ‘Transfer’ as per 2(47) (v) of the Income Tax Act. The definition reads as below:
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["transfer"32, in relation to a capital asset, includes
(v) any transaction involving the allowing of the possession of any immovable property to be taken or retained in part performance of a contract of the nature referred to in section 53A36 of the Transfer of Property Act, 1882 (4 of 1882) ;”
4) new property should be purchased in not only in your name and wife name but your father name should also be reflected as co owner of property
5) Section 45 of the Act states that the capital gain is chargeable to tax in the year in which transfer takes place. The term ‘transfer’ has been defined u/s 2(47) of the Act which includes any transaction allowing the possession of the property as per the section 53A of the Transfer of Property Act, 1882.
In your case it would when agreement for sale is entered into
stamp duty valuation at time of entering into agreement for sale will be taken as sales consideration for computing the capital gains as the possession is obtained by the buyer during the agreement to sell and the sales consideration is paid through account payee cheques.