Capital gain on amount recd from landlord

Dear All,

My clinet has an office in an appartment which he has taken on Salami Bhada at a monthly rent of Rs.2500 and security depost of Rs.1,50,000 in 1999. Now, landlord has asked my client to vacate the property and giving my clinet Rs.6,00,000 for vacaing the same. 

Now I am confused whether it will be a capital receipt in the hand of my client and thus, no taxes as my client doesnt own the capital asset or he will be liable to pay capital gain. If he is liable to pay capital gain, what will be the cost of acquasition?

This is urgent. Kindly help.

Regards

Barun