Notice for escaped income: pre-notice show cause and specified authority approval required before reassessment notices are issued. Sections 148 and 148A create a pre-reassessment framework: the Assessing Officer may issue a section 148 notice requiring a return only where information suggests income has escaped assessment; specified categories of information are enumerated. Returns after the notice deadline are not returns under section 139. Section 148A requires service of a show cause notice with accompanying information and an opportunity to reply; issuance of a section 148 notice thereafter must be authorized by the specified authority. The section 135A scheme is excluded from the pre-notice procedural requirement.