When books of accounts is to be audited???

1) Business: Total Sales, Turnover, Gross receipts, in business for the previous year relevant to the assessment year exceeds 
Rs. 40 Lakhs for AY 2010-11 or 
Rs. 60 Lakhs from AY 2011-12 onwards

2) Profession : Gross receipts for the Previous year relevant to the assessment year exceeds 
Rs. 10 Lakhs for AY 2010-11 or 
Rs. 15 Lakhs from AY 2011-12 onwards

3) Where the assessee has claimed lower income than as prescribed u/s 44AE, 44BBor 44BBB.

4) Where the assessee has claimed lower income than as prescribed u/s 44AD and his income exceeds the maximum amount which is not chargeable to income-tax during such previous year.( From AY 2011-12)

For more detail.........click here.Sec 44ab