Limitation period for income-tax reassessment: reopening allowed only where escaped income is evidenced as asset or expenditure, triggering notices for each year. Amendment substitutes clause (b) of section 149(1) to permit reopening between three and ten years only where books, documents or evidence show escaped income represented as an asset, expenditure related to a transaction or event, or book entries reaching the statutory monetary threshold; it deems a related proviso substituted from a retrospective date and inserts a provision requiring a separate reassessment notice for each prior year when such escaped income is invested or incurred across multiple years.