Exemption of Capital Gain u/s 54

The seller should purchase a residential house either 1 year before the date of sale/transfer or 2 years after the date of sale/transfer. In case the seller is constructing a house, the seller has an extended time, ie. the seller will have to construct the residential house within 3 years from the date of sale/transfer. In case of compulsory acquisition, the period of acquisition or construction will be determined from the date of receipt of compensation (whether original or additional compensation)

Agree  with  Sourav  , one of the condition  under section 54  is ,  Your  New  residential  Flat  Should be  Constructed  with  in  Three years  from the date of Transfer  (sale )   and  second  condition   is   you can not  sale  new Flat  within   three  years  .

Old flat capital gain will be taxable and no relief under section 54.

Nowadays construction flat in big gated community is taking 4 to 5 years . For the purpose of exception capital gains selling a residential property & getting allotment letter for buying a new flat in the same year or within one satisfy the condition .