Capital gain tax period for under construction property

The flat should be constructed within a period of 3 years from the date of transfer.  If the same is not constructed within 3 years from the date of sale and the CG remains unutilized on or before the due date of filing teh return of incoem, then you ahve to deposit the unutilised CG in the Capital Gains Accounts Deposit Scheme.  The receipt given by the bank would be sufficient evidence for claiming exemption from CG for that eyar.

However after completion of the flat, the copy of the Sale Deed should be sufficient evidence for claiming exemption u/s 54 after 3 years.