Capital gain

1) Amount Forfeited by the seller (i.e, Rs 40 lakhs) is a dead loss for you and you are not eligible to claim deduction u/s 54B for such amount.

2) Your are still liable to pay tax on capital gain of Rs60 lakhs.

Planning:

1)deposit Rs60 lakhs in Capital Gain deposit account before the due date of filing ITR u/s 139(1) or

2) purchase another land

if you are going to purchase another agriculture land than purchase such land in a rural area because  capital gain is exempted on rural agriculture land