Time limits for recomputation under Section 155 set statutory windows for amending assessments and recomputations of income. Section 155 prescribes statutory windows and procedural requirements for amendment of past assessments or recomputation of total income in enumerated situations. Most categories permit amendment within four years from the end of the relevant previous or financial year, while specified cases provide distinct shorter windows-including an application window for credit of tax deducted in a later year and an expedited recomputation timetable tied to transfer pricing determinations. The provision links each triggering event to its applicable timebar and any required application or formality.