Time limits for reopening assessments limit notices under sections 148/148A; extensions apply where AO holds evidence of significant escaped income. The substituted provision sets limitation periods for reopening assessments: notices under section 148 are barred after three years and three months, with an extension up to five years and three months if the Assessing Officer has books, documents or evidence showing escaped income amounting to or likely to amount to fifty lakh rupees or more; notices to show cause under section 148A are barred after three years, subject to extension up to five years where information with the Assessing Officer indicates escaped income amounting to or likely to amount to fifty lakh rupees or more.