Return scrutiny permits discrepancy notices; unsatisfactory explanations may lead to assessment or enforcement action. The proper officer may scrutinize a registered person's return and related particulars, inform the person of any discrepancies and seek an explanation; if the explanation is acceptable no further action follows. If no satisfactory explanation is given within thirty days (or extended period) or if accepted discrepancies are not corrected in the return, the proper officer may initiate enforcement measures or proceed to determine tax and other dues under the statutory determination provisions.