Show-cause procedure before issuing notice under section 148 requires an opportunity to reply and prior authority approval. Where the Assessing Officer has information suggesting escaped taxable income, he must serve a notice to show cause accompanied by that information and allow the assessee time to reply; thereafter, taking into account the reply and material on record, the Assessing Officer shall, with the prior approval of the specified authority, decide whether it is a fit case to issue a notice under section 148. The pre-notice procedure does not apply to cases arising from searches or requisitions or from information received under the notified scheme.