Scrutiny of returns: officer can seek explanations and, if unsatisfactory, initiate assessment or enforcement actions. Section 61 authorizes the proper officer to scrutinize returns and related particulars, notify discrepancies and seek explanations; if explanations are accepted, no further action follows, but if explanations are unsatisfactory or corrective measures are not taken in the subsequent return within the prescribed period or extension, the officer may initiate appropriate assessment or enforcement actions or proceed to determine tax and other dues.