If you are running a business, then you need to get your books accounted for if total sales exceed Rs.1 crore.
If you are a professional earning income in excess of Rs. 25 lakhs, then you need to get your books audited.
From FY 2016-17, the limit has been increased from Rs. 1 crore to Rs. 2 crores and Rs. 25 lakhs to Rs. 50 lakhs.