1. Sec 44AD assessee is not required to maintain books of accounts u/s 44AA and thus it would be unfair from the assessee point of view to expect to deduct TDS u/s 192 when in fact he had not maintained any books of accounts.
2. Unlike in sec 194-C where it was clearly mentioned that for the person who is not required to carry on tax audit u/s 44AB is not required to deduct TDS u/s 194C, but there is no express provision u/s 192 as such.
3. Sec 44AD had mentioned sec 30 to 38 alone to be allowed as deduction and disallowance u/s 40(a)(ia) was not covered under the same, an angle could be taken that disallowance u/s 40(a)(ia) could have been made if he had not deducted the same.
4. However in the case of I.T.O. Vs Mark Construction (ITAT Kolkata) the doubt was cleared by ITAT that there is no disallowance u/s 40(a)(ia) in case if a person had opted for presumptive taxation u/s 44AD.
5. Based on the above analysis, disallowance u/s 40(a)(ia) will not be attracted for non-deduction of TDS, if he had opted for presumptive taxation scheme u/s 44AD.
Please correct me if the above interpretation has an alternative view.