Escaped assessment notice procedure governs when income notice may issue, the return period, and prior approval safeguards. Issue of notice before assessment, reassessment or recomputation where income has escaped assessment requires the Assessing Officer to serve a notice and require a return within a specified period, subject to a minimum of thirty days and a maximum linked to the month of issue. The return is treated as a return under section 263 only if filed in time. A notice may be issued only where the Assessing Officer has information suggesting escaped assessment, and prior approval is required in specified cases.