book maintain limit

Maintainance of books of accounts is mandatory u/s. 44AA.........

i.e. when business income exceeds Rs. 1,20,000/- or turnover of the business exceeds Rs. 10,00,000/=

when turnover in  share market is of business nature....... the same limit applies.

For more details: refer page 74 of the slide: 

slideshare.net/praveenpammy/presentation-on-income-tax-ay-2009-10-2010-11

For mandatory tax audit  of any business section 44AB applies, and the limit for the same was 40 lakhs for AY 2009-10 (unless opted for sec 44AD)