It is not necessary that the assessee had to declare only the minimum amount in presumptive returns.

In fact he can volantarily declare the minimum amount or the actual amount whichever is higher. The intention of the law is to make the filing easy for the tax payer and that he should not maintain accurate accounts.

But all businessmen/ professionals maintain rough accounts. It is a part of business. In my opinion, at least a rough Profit and loss account & balance sheet should be made before filing returns especially if the clients needs bank loans.