In case of a transporter, you have to first see whether he owns more than 10 trucks or not. (a) If he does not own more than 10 trucks then he can opt presumptive taxation scheme under Section 44AE irrespective of the turnover. (b) If he owns more than 10 trucks, he is NOT eligible for u/s 44AE and his income will be computed as per the normal provisions. If he falls in (b) above, the turnover limit for tax audit u/s 44AB is 1 crore.