Hi Bruno. the sale should be within one year from the date the trasnfer took place.
Yes to claim the exemption, you will be required to file your I-T return on or befoer the due date of furnishing your I-T Return. In that the detailed of calculation of the Capital Gains should be given as below:
Sale Consideration xxxxxx
Less: Brokerage Paid xxxx
Indexed Cost of Acquisition xxxxxx xxxxxx
Long Term Capital Gains xxxxxx
Less; Exemption u/s 54 xxxxxx
LTCG chargeable to tax xxxxx
If the Cost of Acquisition of the new house is less then the Capital Gains then on the balacne you wud be requried to pay LTCG tax @ 20%.
Your Indexed COA would be the Cost of the Acquisition of the house purchased multiplied by Cost Inflation Index for the year when the sale took place divided by Cost Inflation Index of the Year when the property was being purchased.