Tax credit and capital gain assessment corrections require amendment when supporting valuation or certificate is later produced. The amendment requires the Assessing Officer to amend assessments or intimations where tax credit certificates are later produced within the specified two-year window, provided the relevant income was disclosed in the return, and to amend capital gains assessments where stamp-duty valuation is subsequently revised on appeal, applying the procedural amendment provisions and reckoning the amendment period from the year in which the revising order was passed.