Capital gain investment timeline sale of property

Within one year before registered sale agreement. (Or two years after that)

Ok , thanks, just to confirm, i can sell old one 2 years after the sale agreement of new property and the construction of new one should finish within 2 years of sale?

Yes, eligible, if you pay (at least) the capital gain amount to builder before filing relevant ITR.

An under-construction property ready in 2027:

• For Sec 54/54F, construction must be completed within 3 years from the date of transfer (sale) of the original asset. If you sold in, say, 2024 and the new flat (booked from a builder) completes in May 2027, it must be within 3 years of the sale date.

• CBDT Circular 471/1986 treats allotment of a builder flat as "construction". Payments to the builder within the period count, and completion of construction within 3 years is the test (tribunals are lenient where the delay is due to the builder).

• Deposit the unutilised amount in the CGAS before the ITR due date, and withdraw it as instalments are paid.